Premium
LiClO 4 ‐katalysierte nucleophile Addition an α‐chirale Aldehyde, Aldimine und Oxirane
Author(s) -
Ipaktschi Junes,
Heydari Akbar
Publication year - 1993
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19931260822
Subject(s) - chemistry , ketene , acetal , aldimine , nucleophile , trimethylsilyl cyanide , aldehyde , medicinal chemistry , silylation , nucleophilic addition , lithium perchlorate , diastereomer , trimethylsilyl , organic chemistry , stereochemistry , catalysis , electrode , electrochemistry
LiClO 4 ‐Catalyzed Nucleophilic Addition to α‐Chiral Aldehydes, Aldimines, and Oxiranes The diastereoselectivity of lithium perchlorate‐induced addition of trimethylsilyl cyanide and O ‐silylated ketene acetals to α‐chiral aldehydes is studied. Whereas aldehyde 1 reacts with the ketene acetal 2 exclusively to form the syn ‐ester 3 , a divergent selectivity is observed in the case of trimethylsilyl cyanide addition to 5 and 11a–c . Also the reaction of O ‐silylated ketene acetals with aldimines 16 in the presence of lithium perchlorate proceeds smoothly to afford the corresponding β‐amino esters 17 in high yields. While the silyl ketene acetal of methyl acetate leads preferentially to the corresponding anti ‐diastereomer, in the case of the silyl ketene acetal of methyl isobutyrate a syn‐/anti ‐selectivity in the range of 79:21 to 44:56 is observed. In the presence of lithium perchlorate solution in ether the oxiranes 27a–d undergo facile nucleophilic ring opening reactions with 2, 29 , and 30 .