1,2-ADDITION VS 1,4-ADDITION OF NUCLEOPHILIC ORGANOMETALLICS TO NONRACEMIC 2-(1-NAPHTHYL)-1,3-OXAZOLIDINES AND 2-CINNAMYL-1,3-OXAZOLIDINES

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 primarily 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 excesses of 93-94%. The amino alcohol products resulting from 1,2-addition were oxidatively cleaved to afford enantiomeric enriched (R)-alpha-(1-naphthyl)alkylamines 6a and 6b in > 99% ee.