RESULTS: INTRAMOLECULAR CYCLIZATION.


Reaction Conditions:
i) BuLi / THF -78°C
ii) air
iii) MsCl /CH2Cl2 / Et3N 0°C
iv) DMF / NaH 45°C

DISCUSSION

The complexed beta-hydroxysulfonamide 9 was obtained in 89% yield and as single diastereoisomer. The enantiomeric excess determined by 1H NMR with Eu(hfc)3 on product 11 was higher than 98%. The cyclization of 11 in DMF/NaH at 45°C affords the expected beta- sultam 12 in 98% yield and in e.e. 98% .

On the basis of accepted stereochemical model for the chromium arene derivative, we think that it is resonable to assign the 3R configuration to product 12.

A similar yield and e.e. purity was obtained when the complex of 2-OMe tricarbonylchromium benzaldehyde was used as starting material.



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