Penicillin Acylase-Mediated Synthesis of 2-Acetyl-1-pyrroline and of 2-Propionyl-1-pyrroline, Key Roast-Smelling Odorants in Food. Inclusion Complexes with beta-Cyclodextrin and Their NMR and MS Characterization

J Org Chem. 1996 Dec 13;61(25):8975-8979. doi: 10.1021/jo961474c.

Abstract

The synthesis of the strong natural roast odorants 1 and 2 is achieved from the C-6 isomeric alcohols 16 and 21 via the acetylenic C-6 and C-7 amines 8 and 9. Key step in the process is the hydrolysis of the N-phenylacetamides 12 and 13 by means of immobilized penicillin acylase, which affords the 1-amino-4,5-diketones 14 and 15, spontaneously ring closing to 1 and 2. These latter compounds form inclusion complexes with beta-cyclodextrin, as demonstrated by NMR measurements in deuterated water and FAB-MS spectra.