A. Zietlow, E. Steckhan
Sep 1, 1994
Citations
0
Influential Citations
25
Citations
Journal
Journal of Organic Chemistry
Abstract
(4S,4R)-4-Methoxy-5-methyl-2-oxazolinone (2ab), easily obtained by electrochemical decarboxylative methoxylation of the cyclic L-threonine derivative (4S,5R)-5-methyl-2-oxazolidinone-4-carboxylic acid (1), acts as effective diastereoselective amidoalkylation reagent. The methoxy group exchange in 2ab can be performed with higher order organocuprates (R 3 Cu 2 Li) in the presence of BF 3 .OEt 2 . The 4-alkyl- or 4-aryl-substituted 2-oxazolidinones 9-6 can be obtained with trans diastereoselectivities between 75 and 98% in S N 1 fashion via the intermediate N-acylimine. On the contrary, the N-methylated (4RS,5R)-4-methoxy-3,5-dimethyl-2-oxazolidinone (7ab) undergoes methoxy group exchange under identical conditions mainly via the S N 2 mechanism. Thus, starting from trans-7a mainly cis-8b is formed with 76% ds. The described procedures make cis- or trans-4-alkyl-5-methyl-2-oxazolidinones and the respective dichiral 2-amino alcohols selectively available by a short reaction sequence