142484-00-2Relevant articles and documents
Model Studies of the Reduction of 3-Phenyl-6H-1,2-oxazines, Chemo- and Stereoselectivity: Synthesis of Amino Alcohols, Amino Acids, and Related Compounds
Zimmer, Reinhold,Hoffmann, Matthias,Reissig, Hans-Ulrich
, p. 2243 - 2248 (2007/10/02)
While palladium-catalyzed hydrogenation of 3-phenyl-6H-1,2-oxazine 1 produces primary amine 5 in a nitrogen-transposition reaction, the reductions of the related 1,2-oxazines 2, 10, and the 1,2-oxazin-6-one 3 afford the expected amino alcohols 4, 11, and the γ-amino acid 6, respectively, with low diastereoselectivities.In the presence of acetic acid 3 is reductively converted into γ-keto carboxylic acid 9 and 1 into the γ-lactam derivative 12 probably by a ring contraction to a nitrone intermediate.Raney nickel as the catalyst is able to transform 1,2-oxazine 7 bearing an exo-methylene unit into 3,4-dihydro-2H-pyrrole 13.The reaction of 6H-1,2-oxazine 1 with aluminium amalgam produces pyrrole 14 in moderate yield.Treatment of 1 with sodium in 2-propanol brings about its transformation into pyrrolidine derivative 15 together with pyrrole 14 and amino alcohol 4 as minor products.The chemoselectivity and stereoselectivity of these reductions are discussed including mechanistic proposals for the multistep processes involved. Key Words: 1,2-Oxazines / Hydrogenation, catalytic / Amino alcohols / γ-Amino acids / Pyrroles / γ-Lactams
