Abstract
A number of N‐acryloyl‐, N‐crotonoyl‐, N‐(3,3,3‐trifluorocrotonoyl)‐, N‐cinnamoyl‐, and N‐(3‐nitroacryloyl)‐4‐isopropyl‐ or ‐4‐phenyl‐oxazolidin‐2‐ones with geminal diphenyl substitution, i.e., 7–15, have been prepared and used for conjugate additions of organocuprate reagents (Me, ^i^Pr, Ph, 4‐MeOPh) in the β‐carbonyl (Table 2) and in the α‐carbonyl position (NO~2~‐derivative 11 in Scheme 3). The yields and diastereoselectivities are compared with previously tested enoyl‐oxazolidinones (Table 2). Highest diastereoselectivities (>90%) are always observed with the 4‐Ph derivatives (Hruby effect). Nitroacryloyl‐oxazolidinones and a corresponding phenylmenthol ester undergo less diastereoselective additions (Scheme 3). A 3‐(1‐methylethyl)‐5,5‐diphenyloxazolidin‐2‐one (DIOZ)‐derived Li~2~‐enolate‐nitronate was also tested for α‐carbonyl alkylation (Scheme 4). The X‐ray crystal structures of three acryloyl‐oxazolidinones and of four adducts are described (Tables 1 and 3), and they serve for configurational assignments and description of the stereochemical courses of the additions and alkylation. Possible applications of the nitro compounds for the preparation of β^2^‐amino acids are discussed (Scheme 2).