Title

Copper-catalysed Asymmetric 1,4-addition of Organozinc Compounds to Linear Aliphatic Enones Using 2,2′-dihydroxy 3,3′-dithioether Derivatives of 1,1′-binaphthalene

Abstract

Directed ortho dilithiation of bis(diethylcarbamate) or bis(MOM)-protected (Sa)-1,1,′-bi(2-naphthol) followed by treatment with R2S2 [R = Me, Ph (X-ray structure)] or Me2Se2 cleanly affords the 3,3′ derivatives; the free naphthols are produced on deprotection. In the case of the bis(MOM) series, but not that of the bis(carbamates), some racemisation occurs. The ligand 2,2′-dihydroxy-3,3′-dimethylthio-1,1′-binaphthalene shows optimal performance in the addition of ZnEt2 to linear aliphatic enones (E)-R1C(O)CH=CHR2. Variation of the steric demands of R1 and R2 generates catalytic results consistent with binding of a zinc-based Lewis acid anti to the ene function and with the reactive conformation being s-cis. With enones containing the functions R2 = (CH2)nCH(OAlkyl)2 (n = 0-2), the ZnEt2 addition products undergo base-promoted cyclisation.

Department(s)

Chemistry

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2001 ChemPubSoc Europe, All rights reserved.


Share

 
COinS