Grignard reactions of 4-substituted-2-keto-1,3-dioxanes: highly diastereoselective additions controlled by a remote alkyl group.
[see reaction]. The reactions of Grignard reagents with a representative series of simple cis-2-keto-4-substituted-1,3-dioxanes have been investigated. The stereochemical outcome of these highly diastereoselective additions (dr > 90:10) is consonant with Cram's chelate model on the assumption that RMgX coordinates preferentially with the ring oxygen remote from the C(4) substituent.
Bailey
W F
WF
Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, USA. bailey@uconn.edu
Reed
D P
DP
Clark
D R
DR
Kapur
G N
GN