152481-90-8Relevant articles and documents
SYNTHESIS OF THIOALDEHYDES HAVING OPTICALLY ACTIVE ALKOXY MOIETY AND THEIR ASYMMETRIC HETERO DIELS-ALDER REACTION
Takahashi, Tamiko,Kurose, Noriyuki,Koizumi, Toru
, p. 1601 - 1616 (2007/10/02)
Optically active α-alkoxycarbonylthioaldehydes (2a-g) were prepared using 8-arylmenthols as chiral auxiliaries.Their asymmetric hetero Diels-Alder reactions with cyclopentadiene gave the endo cycloadducts (3 and 4) and exo cycloadducts (5 and 6) with moderate diastereomeric excesses.However, the major endo cycloadducts (3b-g) were isolated in optically pure form.This is the first chiral synthesis of 2-thiabicyclohept-5-ene ring system.The absolute configuration of the cyclic carbonate (12), which was prepared from the major endo cycloadduct (3c) via the epimerization, or the minor exo compound (6c), was determined as 1R by X-ray analysis.The cycloadduct (3c) was trasformed to a potential intermediate (14) for the synthesis of carbocyclic homonucleosides.