Formation of pyridin-4(1H)-one versus 1H-azepin-4(7H)-one by treatment of 4-tert-butyldimethylsilyloxy-2-amino-1-aza-bicyclo[4.1.0]hept-3-enes with tetrabutylammonium fluoride
作者:M. José Alves、A. Gil Fortes、F. Teixeira Costa、Vera C.M. Duarte
DOI:10.1016/j.tet.2007.08.007
日期:2007.11
Cycloadducts 3 and 4 were treated with tetrabutylammonium fluoride and rapidly suffer cleavage on the three-membered ring to form either pyridin-4(1H)-one or 1H-azepin-4(7H)-one. When R-1 is an oxycarbonyl or a 2-pyridyl group and R-2 is a negative charge-stabilizing group (cases 3a,b and 4f) the C-C bond cleaves forming products 5. However, when R-2 = H (case 3c) the ring expands to seven members. When R1 is an acyl group the pyridin-4(1H)-one formation includes an unexpected shift of the carbonyl group. (c) 2007 Elsevier Ltd. All rights reserved.
Ethyl 3-(2-Pyridyl)-2<i>H</i>-azirine-2-carboxylate: Synthesis and Reaction with Dienes
作者:M. Alves、A. Gil Fortes、Américo Lemos、Cristina Martins
DOI:10.1055/s-2004-837296
日期:——
Ethyl 3-(2-pyridyl)-2H-azirine-2-carboxylate, the first example of an 3-heteroamatic 2H-azirine has been prepared. The re- action of ethyl 3-(2-pyridyl)-2H-azirine-2-carboxylate with conju- gated 1,3-dienes, under mild conditions and in the absence of Lewis acid catalyst, afforded cycloadducts in good yield and high stereo- selectivity.
Diels–Alder cycloaddition of electrophilic 2H-azirines with 3-(3-(tert-butyldimethylsilyloxy)buta-1,3-dienyl)oxazolidin-2-ones. Treatment of the cycloadducts under acidic conditions
作者:M. José Alves、A. Gil Fortes、F. Teixeira Costa
DOI:10.1016/j.tet.2006.01.035
日期:2006.3
3-(3-(tert-Butyldimethylsilyloxy)buta-1,3-dienyl)oxazolidin-2-one was reacted with several electrophilic 2H-azirines to give the expected cycloadducts in moderate to good yields. Treatment of the cycloadducts under acidic conditions gave six-membered ring aminoenones and aziridine derivatives. In the case where anilinium fluoride was used an inversion at the C-2 stereogenic center was observed forming an