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Intramolecular ring opening of a 2,3-epoxy alcohol by a xanthate anionic center; stereospecific preparation of 2-mercapto-1,3-diol units

✍ Scribed by Jun'ichi Uenishi; Mitsuhiro Motoyama; Yoshitaka Nishiyama; Yuichi Hirota; Yuki Kubo; Haruo Akashi

Publisher: John Wiley and Sons
Year: 1994
Tongue: English
Weight: 866 KB
Volume: 5
Category: Article
ISSN: 1042-7163
DOI: 10.1002/hc.520050110

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✦ Synopsis

Stereospecific ring openings of optically active 2,3epoxy alcohols were performed by the reaction of 1, 3,5, and 7 with curbon disulfide and sodium hydride to give the five-membered xanthates 2, 4, 6, and 8. Both enantiomers of 2-mercapto-l,3-diol triacetates, 11 and 14, were derived from 4 and 6, respectively. The ring opening reaction proceeded at -78°C to -3O"C, and the yields were around 80%. However, at a higher temperalure between 0°C to room temperature, a complicated reaction took place and led to the formation of two isomers o f the cyclic thiol carbonates 15 and 16 from 1 or 5. These processes were also stereospecific, and mechanisms have been proposed. I n the case of the 3,4-epoxy alcohol 20, the epoxide ring opening gave the six-membered xanthate 21 stereospecifically.

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