{"id":31413,"date":"2026-06-01T09:24:21","date_gmt":"2026-06-01T08:24:21","guid":{"rendered":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413"},"modified":"2026-06-01T10:00:54","modified_gmt":"2026-06-01T09:00:54","slug":"a-1965-precedent-to-the-dewar-pyrimidone-most-system-and-text-book-examples-of-the-woodward-hoffmann-pericyclic-selection-rules","status":"publish","type":"post","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413","title":{"rendered":"A 1965 precedent to the Dewar Pyrimidone MOST system – and text book examples of the Woodward-Hoffmann pericyclic reaction selection rules"},"content":{"rendered":"
\n

In the previous post,[1]<\/a><\/span> I noted the photochemical isomerisation of a pyrimidone into what is called the bicyclic Dewar form, being part of a solar energy storage system.[2]<\/a><\/span> A colleague (thanks Alan!) has recollected a very similar example dating from 1965[3]<\/a><\/span> in which a similar molecule known as a diazepinone 72<\/strong> (scheme below) is converted by light into a Dewar form 73<\/strong>.<\/p>\n

This example was first highlighted\u00a0in Woodward and Hoffmann’s (WH) famous 1971 book on the topic of the conservation of orbital symmetry\u2020<\/sup> in which they noted that the Dewar form\u00a0of a diazepinone (73<\/strong> in scheme) had been observed[3]<\/a><\/span> to thermally “revert to diazepinone in the dark”.\u2020<\/sup> The original authors[3]<\/a><\/span> also specifically noted that the Dewar diazepinone was “stable to storage” after being protonated. These two properties are the exact inverse of the recent report,[2]<\/a><\/span> whereby the photochemical bicyclic form of pyrimidone was found to be thermally stable, but very rapid ring opening was induced by protonation with acid. Here I explore whether these apparently contradictory reports can be reconciled.<\/p>\n

\"\"<\/a><\/p>\n

In discussing the reaction of 72<\/strong> in their book\u2021<\/sup>, WH suggest that the stereochemical aspects of the thermal ring opening of 73<\/strong> could be explained using their rules\u00a0by prior inversion of the ring nitrogen stereochemistry to that of 73-inv<\/strong>, followed by conrotatory\/antarafacial ring opening to 72<\/strong>. Here, with the help of \u03c9B97XD\/Def2-TZVPP\/DCM DFT calculations,[4]<\/a><\/span> I discuss whether this suggestion is viable, and also propose an alternative mechanism (72-trans<\/strong>, Scheme above).<\/p>\n

Firstly, I show the calculated reaction path[5]<\/a><\/span>,[6]<\/a><\/span> along which HTS3<\/strong> and 73-inv<\/strong> are found, being the WH suggestion for this reaction.<\/p>\n

\"\"
\n\"\"
\nFigure 1.<\/b> IRC Energy plot and animation for TS3<\/strong><\/p>\n

    \n
  1. At IRC ~8, (Figure 1) the potential shows what can be called a “hidden transition state”, at which point the gradient norm is close to zero. This is the point labelled HTS3<\/strong>, followed soon after by a “hidden intermediate” (IRC ~4) or 73-inv.<\/strong> The process corresponds to inversion of the nitrogen lone pair to produce a bicyclic species with a trans<\/em> ring fusion. These are both “hidden” because the gradient norm (Figure 2) does not actually reach a value of 0.0 as required for “real” transition states and intermediates, but comes very close.<\/li>\n
  2. \u0394G\u2021<\/sup>298 <\/sub>at these points\u00a0relative to the starting\u00a0point is ~34 kcal\/mol, rather higher than would be needed for a truly thermal reaction. The CN bond length has not yet started to change (Figure 3).<\/li>\n
  3. At IRC = 0.0 the true transition state is reached (TS3<\/strong>), involving WH-allowed antarafacial cleavage (Figure 5) of the bicyclic C-N bond (length @TS 2.035\u00c5). The energy is now ~65 kcal\/mol above the starting point, which makes this pathway very unlikely.<\/li>\n
  4. The thermal reaction is exothermic by -19 kcal\/mol (Figure 1), significantly less than that for Dewar pyrimidone.<\/li>\n<\/ol>\n

    \"\"<\/p>\n

    Figure 2. <\/b>Gradient norm plot for TS3<\/p>\n

    \"\"<\/a>
    \nFigure 3. <\/b>C-N bond length plot for TS3<\/strong><\/p>\n

    \"\"<\/a>
    \nFigure 4. <\/b>Dipole moment plot for TS3<\/strong>, just for fun!<\/p>\n

    \"\"
    \nFigure 5. <\/b>Geometry of TS3<\/strong>,\u00a0showing C-N bond with antarafacial component (top face connecting bottom face) corresponding to conrotation (both clockwise) of the two termini.<\/p>\n

    Next, I tried an alternative mechanism, involving direct ring opening via<\/em> TS1 <\/strong>to give a 7-ring with a trans<\/em> bond, 72-trans<\/strong>. [7]<\/a><\/span>,[8]<\/a><\/span>\u00a0(Figure 6). Back in 1971, 7-rings with trans<\/em> bonds were a rarity, so WH were probably reluctant to suggest this.<\/p>\n

    \"\"<\/a>
    \nFigure 6. <\/b>Energy plot for TS1<\/strong><\/p>\n

      \n
    1. The activation energy (corresponding to \u0394G\u2021<\/sup>298 <\/sub>27.84 kcal\/mol) is looking much better, matching to a slow (hours, days) thermal reaction at room temperatures. This value is somewhat less than the value of 32.9 kcal\/mol for the analogous ring opening of Dewar pyrimidone,[1]<\/a><\/span> probably because the larger 5-ring ring means less transition state strain.<\/li>\n
    2. The reaction again occurs with conrotation\/antarafacial (Figure 7), C-N 2.192\u00c5.<\/li>\n
    3. But it is now endothermic by about +15 kcal\/mol, reflecting the relatively high energy of a 7-ring product with a trans<\/em> bond (Figure 6).<\/li>\n<\/ol>\n

      \"\"
      \nFigure 7<\/strong>. Geometry of TS1,<\/strong>\u00a0showing C-N bond with antarafacial component (top face connecting bottom face) corresponding to conrotation (both clockwise) of the two termini.<\/p>\n

      To complete the mechanism, a route must now be found to convert 72-trans<\/strong> back to 72<\/strong> itself.<\/p>\n

        \n
      1. This can be done via a linear arrangement of the C-N-N atoms[9]<\/a><\/span> but the barrier to doing so is prohibitive (\u0394G\u2021<\/sup>298<\/sub> 39.7 kcal\/mol).<\/li>\n
      2. An alternative is direct rotation about the CN bond via<\/em> a biradical transition state (TS2)<\/strong>,[10]<\/a><\/span>,[11]<\/a><\/span> which yields \u0394G\u2021<\/sup>298<\/sub>
        \n26.74 kcal\/mol. This value is less than that for TS1,<\/strong> and so is not rate determining.<\/li>\n<\/ol>\n

        \"\"<\/a><\/p>\n

        Figure 8<\/strong>. Energy plot for TS2<\/strong><\/p>\n

        When TS1<\/strong> is protonated, \u0394G\u2021<\/sup>298<\/sub> becomes 26.4 kcal\/mol (Figure 9, [12]<\/a><\/span>,[13]<\/a><\/span>, C-N 2.198\u00c5) compared to the unprotonated value of \u0394G\u2021<\/sup>298<\/sub> 27.8 kcal\/mol. The slight decrease in barrier upon protonation does not match the observation[3]<\/a><\/span> that protonated 73<\/strong> is “stable to storage”. This still leaves open the question of why computations indicate that the rate of ring opening of Dewar diazepinone is relatively unchanged by protonation, whereas that of Dewar pyrimidone is greatly accelerated – the former involves protonating a hydrazine whereas the latter involves protonating an amide. Further models will need investigating to confirm whether this accounts for the essential difference in behaviour.<\/p>\n

        \"\"<\/a>
        \nFigure 9.<\/b> Energy plot for TS1<\/strong> upon protonation.<\/p>\n

        To conclude, WH’s suggestion of a nitrogen inversion mechanism for the slow thermal pericyclic reaction of 72<\/strong> followed by conrotatory C-N ring opening is instead replaced here by one invoking the electrocylic formation of a 7-ring intermediate with a trans<\/em> bond and then biradical rotation of this bond.<\/p>\n

        \n

        \u2021<\/sup> Woodward, R. B.; Hoffmann, Roald (1971). The Conservation of Orbital Symmetry (3rd printing, 1st ed.). Weinheim, BRD: Verlag Chemie GmbH (BRD) and Academic Press (USA). pp. 1\u2013178. ISBN 978-1483256153. \u2020<\/sup>The kinetics of this process were not noted, nor was the temperature.<\/p>\n

        References<\/h2>\n
        1. H. Rzepa, \"A breakthrough in Molecular Solar Thermal (MOST) energy storage \u2013 Dewar Pyrimidone.\", 2026. https:\/\/doi.org\/10.59350\/jhsbq-sfs70<\/a>\n\n<\/li>\n
        2. H.P.Q. Nguyen, A.J. Maertens, B.A. Baker, N.M. Wu, Z. Ye, Q. Zhou, Q. Qiu, N. Kaur, D.B. Berkinsky, K.E. Shulenberger, K.N. Houk, and G.G.D. Han, \"Molecular solar thermal energy storage in Dewar pyrimidone beyond 1.6 megajoules per kilogram\", Science<\/i>, vol. 392, 2026. https:\/\/doi.org\/10.1126\/science.aec6413<\/a>\n\n<\/li>\n
        3. W.J. Theuer, and J.A. Moore, \"Heterocyclic studies. The photoisomerization of 2,3-dihydro-5-methyl-6-phenyl-4H-1,2-diazepin-4-one and derivatives\", Chemical Communications (London)<\/i>, pp. 468, 1965. https:\/\/doi.org\/10.1039\/c19650000468<\/a>\n\n<\/li>\n
        4. H. Rzepa, \"WH-73\", 2026. https:\/\/doi.org\/10.14469\/hpc\/15948<\/a>\n\n<\/li>\n
        5. H. Rzepa, \"[Embargoed]\", 2026. https:\/\/doi.org\/10.14469\/hpc\/15975<\/a>\n\n<\/li>\n
        6. H. Rzepa, \"73 TS for trans geometry N-epimer ( G =-648.883115 => G = -648.88455 DG = 65.9 IRC mirror image\", 2026. https:\/\/doi.org\/10.5281\/zenodo.20455914<\/a>\n\n<\/li>\n
        7. H. Rzepa, \"73 TS for cis geometry suprafacial, N epimer G = -648.951789 (vs G = -648.933983 for NH isomer ) DG = 27.84 IRC\", 2026. https:\/\/doi.org\/10.14469\/hpc\/15960<\/a>\n\n<\/li>\n
        8. H. Rzepa, \"73 TS for cis geometry suprafacial, N epimer G = -648.951789 (vs G = -648.933983 for NH isomer ) DG = 27.84 IRC\", 2026. https:\/\/doi.org\/10.5281\/zenodo.20279953<\/a>\n\n<\/li>\n
        9. H. Rzepa, \"73 product isomerism G = -648.932844, IRC\", 2026. https:\/\/doi.org\/10.14469\/hpc\/15963<\/a>\n\n<\/li>\n
        10. H. Rzepa, \"73 cis product rotation, G=-648.953525, DG = 26.74\", 2026. https:\/\/doi.org\/10.14469\/hpc\/15967<\/a>\n\n<\/li>\n
        11. H. Rzepa, \"&3 cis product rotation, G=-648.953525\", 2026. https:\/\/doi.org\/10.5281\/zenodo.20406989<\/a>\n\n<\/li>\n
        12. H. Rzepa, \"73 TS for cis geometry N-protonated G = -649.363457 DG = 30.99 => NH epimer G = -649.370744 DG = 26.41 IRC\", 2026. https:\/\/doi.org\/10.5281\/zenodo.20474465<\/a>\n\n<\/li>\n<\/ol>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

          In the previous post, I noted the photochemical isomerisation of a pyrimidone into what is called the bicyclic Dewar form, being part of a solar energy storage system. A colleague (thanks Alan!) has recollected a very similar example dating from 1965 in which a similar molecule known as a diazepinone 72 (scheme below) is converted […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"activitypub_content_warning":"","activitypub_content_visibility":"","activitypub_max_image_attachments":5,"activitypub_interaction_policy_quote":"anyone","activitypub_status":"federated","footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[4,559],"tags":[],"ppma_author":[2661],"class_list":["post-31413","post","type-post","status-publish","format-standard","hentry","category-interesting-chemistry","category-pericyclic"],"yoast_head":"\nA 1965 precedent to the Dewar Pyrimidone MOST system - and text book examples of the Woodward-Hoffmann pericyclic reaction selection rules - Henry Rzepa's Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"A 1965 precedent to the Dewar Pyrimidone MOST system - and text book examples of the Woodward-Hoffmann pericyclic reaction selection rules - Henry Rzepa's Blog\" \/>\n<meta property=\"og:description\" content=\"In the previous post, I noted the photochemical isomerisation of a pyrimidone into what is called the bicyclic Dewar form, being part of a solar energy storage system. A colleague (thanks Alan!) has recollected a very similar example dating from 1965 in which a similar molecule known as a diazepinone 72 (scheme below) is converted […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413\" \/>\n<meta property=\"og:site_name\" content=\"Henry Rzepa's Blog\" \/>\n<meta property=\"article:published_time\" content=\"2026-06-01T08:24:21+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-06-01T09:00:54+00:00\" \/>\n<meta name=\"author\" content=\"Henry Rzepa\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Henry Rzepa\" \/>\n\t<meta name=\"twitter:label2\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"7 minutes\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"A 1965 precedent to the Dewar Pyrimidone MOST system - and text book examples of the Woodward-Hoffmann pericyclic reaction selection rules - Henry Rzepa's Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413","og_locale":"en_GB","og_type":"article","og_title":"A 1965 precedent to the Dewar Pyrimidone MOST system - and text book examples of the Woodward-Hoffmann pericyclic reaction selection rules - Henry Rzepa's Blog","og_description":"In the previous post, I noted the photochemical isomerisation of a pyrimidone into what is called the bicyclic Dewar form, being part of a solar energy storage system. A colleague (thanks Alan!) has recollected a very similar example dating from 1965 in which a similar molecule known as a diazepinone 72 (scheme below) is converted […]","og_url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413","og_site_name":"Henry Rzepa's Blog","article_published_time":"2026-06-01T08:24:21+00:00","article_modified_time":"2026-06-01T09:00:54+00:00","author":"Henry Rzepa","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Henry Rzepa","Estimated reading time":"7 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413#article","isPartOf":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413"},"author":{"name":"Henry Rzepa","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/#\/schema\/person\/2b40f7b9c872a4dc1547e040a11b6281"},"headline":"A 1965 precedent to the Dewar Pyrimidone MOST system – and text book examples of the Woodward-Hoffmann pericyclic reaction selection rules","datePublished":"2026-06-01T08:24:21+00:00","dateModified":"2026-06-01T09:00:54+00:00","mainEntityOfPage":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413"},"wordCount":992,"commentCount":0,"image":{"@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413#primaryimage"},"thumbnailUrl":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2026\/05\/wh-73.svg","articleSection":["Interesting chemistry","pericyclic"],"inLanguage":"en-GB","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413","url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=31413","name":"A 1965 precedent to the Dewar Pyrimidone MOST system - 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A recent breakthrough in such methods has been reported in which a pyrimidone molecule is efficiently converted by 310nm light into the isomeric Dewar pyrimidone. This molecule is thermally\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":9105,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=9105","url_meta":{"origin":31413,"position":1},"title":"The Benzidine rearrangement. Computed kinetic isotope effects.","author":"Henry Rzepa","date":"January 11, 2013","format":false,"excerpt":"Kinetic isotope effects have become something of a lost art when it comes to exploring reaction mechanisms. But in their heyday they were absolutely critical for establishing the mechanism of the benzidine rearrangement. This classic mechanism proceeds via bisprotonation of diphenyl hydrazine, but what happens next was the crux. Does\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":10518,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=10518","url_meta":{"origin":31413,"position":2},"title":"Woodward’s symmetry considerations applied to electrocyclic reactions.","author":"Henry Rzepa","date":"May 20, 2013","format":false,"excerpt":"Sometimes the originators of seminal theories in chemistry write a personal and anecdotal account of their work. Niels Bohr was one such and four decades later Robert Woodward wrote \"The conservation of orbital symmetry\" (Chem. Soc. Special Publications (Aromaticity), 1967, 21, 217-249; it is not online and so no doi\u2026","rel":"","context":"In "pericyclic"","block_context":{"text":"pericyclic","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=559"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":23281,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=23281","url_meta":{"origin":31413,"position":3},"title":"The Stevens rearrangement: how history gives us new insights.","author":"Henry Rzepa","date":"January 29, 2021","format":false,"excerpt":"In a recent post, I told the story of how in the early 1960s, Robert Woodward had encountered an unexpected stereochemical outcome to the reaction of a hexatriene, part of his grand synthesis of vitamin B12. He had constructed a model of the reaction he wanted to undertake, perhaps with\u2026","rel":"","context":"In "Historical"","block_context":{"text":"Historical","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=565"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.ch.ic.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2021\/01\/sden.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":10252,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=10252","url_meta":{"origin":31413,"position":4},"title":"Why diphenyl peroxide does not exist.","author":"Henry Rzepa","date":"April 29, 2013","format":false,"excerpt":"A few posts back, I explored the \"benzidine rearrangement\" of diphenyl hydrazine. This reaction requires diprotonation to proceed readily, but we then discovered that replacing one NH by an O as in N,O-diphenyl hydroxylamine required only monoprotonation to undergo an equivalent facile rearrangement. So replacing both NHs by O to\u2026","rel":"","context":"In "Interesting chemistry"","block_context":{"text":"Interesting chemistry","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=4"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":11642,"url":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?p=11642","url_meta":{"origin":31413,"position":5},"title":"Avoided (pericyclic) anti-aromaticity: Reactions of t-butyl-hydroxycarbene.","author":"Henry Rzepa","date":"November 13, 2013","format":false,"excerpt":"Not long ago, I described a cyclic carbene in which elevating the carbene lone pair into a \u03c0-system transformed it from a formally 4n-antiaromatic \u03c0-cycle into a 4n+2 aromatic \u03c0-cycle. From an entirely different area of chemistry, another example of this behaviour emerges; Schreiner's trapping and reactions of t-butyl-hydroxycarbene, as\u2026","rel":"","context":"In "pericyclic"","block_context":{"text":"pericyclic","link":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/?cat=559"},"img":{"alt_text":"H-mig","src":"https:\/\/i0.wp.com\/www.ch.imperial.ac.uk\/rzepa\/blog\/wp-content\/uploads\/2013\/11\/H-mig.gif?resize=350%2C200","width":350,"height":200},"classes":[]}],"jetpack_likes_enabled":false,"authors":[{"term_id":2661,"user_id":1,"is_guest":0,"slug":"admin","display_name":"Henry Rzepa","avatar_url":"https:\/\/secure.gravatar.com\/avatar\/897b6740f7f599bca7942cdf7d7914af5988937ae0e3869ab09aebb87f26a731?s=96&d=blank&r=g","0":null,"1":"","2":"","3":"","4":"","5":"","6":"","7":"","8":""}],"_links":{"self":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/31413","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=31413"}],"version-history":[{"count":73,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/31413\/revisions"}],"predecessor-version":[{"id":31512,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=\/wp\/v2\/posts\/31413\/revisions\/31512"}],"wp:attachment":[{"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=31413"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=31413"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=31413"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.ch.ic.ac.uk\/rzepa\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fppma_author&post=31413"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}