ISSN:
0009-2940
Keywords:
Ketene acetals, O-silylated
;
Aldehydes, α-alkoxy
;
α-Amino aldehydes
;
Mukaiyama aldol reactions
;
Cyanhydrines
;
Aldimines
;
β-Amino esters
;
Diastereoselektivity
;
Oxiranes
;
Ring opening
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
LiClO4-Catalyzed Nucleophilic Addition to α-Chiral Aldehydes, Aldimines, and OxiranesThe 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.
Additional Material:
6 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931260822
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