1,2- vs 1,4-Addition of Nucleophilic Organometallics to Nonracemic 2-(1-Naphthyl)- and 2-Cinnamyl-1,3-oxazolidines

Article abstract of DOI:10.1021/jo00030a035

We herein report our results where the addition of organomagnesium reagents to 2-(1-naphthyl)- and 2-cinnamyl-1,3-oxazolidines occurred consistently in a 1,4-conjugate manner, while lithium, cerium and copper organometallic reagents added in a 1,2 fashion.The 1,4-conjugate addition pathway was primarely exploited by using (4R)-2-(1-naphthyl)-4-phenyl-1,3-oxazolidine (4) as a substrate to obtain, after NaBH4 reduction of the intermediate aldehyde, trans-disubstituted 1,2-dihydronaphthalenes with enantiomeric excess of 93-94percent.The amino alcohol products resulting from1,2-addition were oxidatively cleaved to afford enantiomeric enriched (R)-α-(1-naphthyl)alkylamines 6a and 6b in <*>99percent ee.