First of all, I apologize for this tardy answer to your questions
concerning our poster 31.
Ca(BH4)2 was tried successfully in this two steps reduction after
initial attempts with LiAlH4 and NaBH4.
Actually, direct reduction of diacid 5 with LiAlH4 only yielded
degradation products and reduction of lactones 6 with NaBH4 (DME/H2O)
afforded a mixture of epimeric diols. At present, we don't tried either
NaBH4/EtOH or LiBH4 which could presumably work fine. A recent exemple of
lactone reduction with Ca(BH4)2 is described in Tetrahedron vol.50 No4
pp1153 (1994) by Yannick Landais et al. See also a very interesting
comparative study of Li, Na and Ca borohydrides by H.C. Brown et al.: J.
Org. Chem. Vol47 4702 (1982).
Concerning the addition of reagents other than alcoholates to
vinylsulfoxides, we previously observed the succesfull addition of amines
(Ch. Maignan et al.Synthesis 547 (1992) and references therein) and
thiolates (unpublished results).
With best regards,
Laboratoire de Synthese Organique
Faculte des Sciences
Universite du Maine
Avenue Olivier Messiaen
F-72017 LE MANS
Telephone: (33) 43 83 33 71
Fax: (33) 43 83 33 66
E-Mail : email@example.com