DESILYLATIVE ELIMINATION OF THE QUINAZOLINONE RING FROM 1-(4-OXOQUINAZOLIN-3-YL)-2-SILYLAZIRIDINES - PREPARATION OF AN N-H AZIRIDINE IN HIGH ENANTIOMERIC EXCESS BY IN-SITU NUCLEOPHILIC-ADDITION TO THE DERIVED AZIRINE

Aziridination of vinylsilanes PhCH=CHSiR(3) (R = Me, Pt, Ph) with enan tiopure 3-acetoxyaminoquinazolinone 11 gives the corresponding aziridi nes 12 [diastereoisomer ratio (dr) 10:1], 18(dr 13:1) and 20 (dr 2:1). Desilylative elimination of the quinazolinone from these aziridines b y caesium fluoride in the presence of cyanide gives aziridine 14 by cy anide addition to the 3-unsubstituted azirine 13, produced in situ. Ac ylation of aziridine 14 with (S)-acetoxypropionyl chloride gives N-acy laziridine 16; the good correlation between the diastereoisomer ratios of aziridines 12, 18 and 20 and those of the N-acylaziridine 16 produ ced in each case suggests that intermediate azirine 13 is configuratio nally stable.