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Enantioselective addition of (Z)- and (E)-alkenylzinc bromides to aldehydes: asymmetric synthesis of sec-allylalcohols

✍ Scribed by Wolfgang Oppolzer; Rumen N. Radinov

Book ID: 104225904
Publisher: Elsevier Science
Year: 1991
Tongue: French
Weight: 249 KB
Volume: 32
Category: Article
ISSN: 0040-4039
DOI: 10.1016/s0040-4039(00)93553-6

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✦ Synopsis

In situ prepared (Z)-and (E)-1 -alkenylzinc bromides 5 were added to various aldehydes 1 in the presence of lithiated (+)-N-methylephedrine or (+)-2-(NJ-dimethylamino)-1,2_diphenylethanol to give sec. allylalcohols 7 in high optical purity with simple recovery of the chiral amino1 6. Asymmetric ligand-controlled additions of diethyl-and dimethylzinc to aldehydes have been subject of numerous studies during the last five years. 1 ) Related additions of alkynylzinc reagents proceeded with variable rface discrimination. 2, Uniformly high inductions were found in our laboratories on reaction of divinylzinc (2) with various aldehydes 1 in the presence of camphor-derived tridentate ligand 3 (Scheme 1). 3) Scheme 1 0 si K i' + Q pz,,A HO' H 1 R' 2 4 82 to >96% e.e

We report here an even more attractive approach to synthetically important p-substituted, chiral allylalcohols.

Our results are summarized in the Scheme 2 and the Tables 1,2. 4, Scheme 2

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