Regioselective Functionalization. 7.<sup>1</sup> Unexpected Preferences for Bridgehead Migration in Schmidt Rearrangement Syntheses of Novel 2,6-Diazabicyclo[3.2.<i>x</i>]alkan-3-ones (<i>x</i> = 1−3)
作者:Grant R. Krow、Steven W. Szczepanski、Jee Y. Kim、Nian Liu、Askia Sheikh、Yushi Xiao、Jing Yuan
DOI:10.1021/jo981977d
日期:1999.2.1
Regioselective syntheses of 2,6-diazabicyclo[3.2.x]alkan-3-ones (x = 1-3) 34 by insertion of nitrogen next to the bridgehead (BH) of 2-azabicyclo[2.2.x]alkanones 32 with hydroxylamine-O-sulfonic acid are described. The ketones 32 under Schmidt reaction conditions (HN3/H2SO4) afford major amounts of BK migrated lactams 34 but also, when x = 2 or 3, the methylene (IM) migrated lactams, 3,6-diazabicycl[3.2.x]alkan-2-ones 37. The present N-insertion reactions favoring BH migration with azabicyclic ketones contrast markedly with reactions of the related carbocycles la,b, which give only methylene migrated lactams 2a,b with HN3/H2SO4. Schmidt reactions of 3-anti/syn-methyl- and 3-anti-phenyl-2-azabicyclo[2.2.2]octan-5-ones 17, 20, and 23 (64:36 +/- 9, BH:M) follow the reaction pattern of the parent ketone 14, but the S-syn-phenyl ketone 26 gives major (65%) methylene migration. The results offer insights into the BH vs M migration dichotomy for the Beckmann and Schmidt reactions of bridged bicyclic ketones.
Lowe John A., III, Drozda Susan E., McLean Stafford, Bryce Dianne K., Cra+, J. Med. Chem, 37 (1994) N 18, S 2831-2840
作者:Lowe John A., III, Drozda Susan E., McLean Stafford, Bryce Dianne K., Cra+
DOI:——
日期:——
Lowe III; Drozda; McLean, Journal of Medicinal Chemistry, 1994, vol. 37, # 18, p. 2831 - 2840