Photochemical and thermal cyclizations of 4-(2-azidophenyl)-3,4-dihydropyrimidin-2-ones for the synthesis of 4-methylenepyrimidino[5,4-b]indol-2-ones
摘要:
Photochemical and thermal cyclization of 4-(2-azidophenyl)-3,4-dihydropyrimidin-2-ones could afford fused indoles, such as 1,2,3a,9b-tetrahydro-4-methylenepyrimidino[5,4-b]indol-2-ones and 1,3,5,6,7a, 12b-hexahydroquinazolino[9,4-b]indol-2,7-dione in high yields via nitrene electrophilic addition and rearrangement reactions. (C) 2010 Elsevier Ltd. All rights reserved.
New efficient synthesis of pyrimido[1,6-c]quinazolin-4-ones by a Biginelli 3CC/Staudinger/aza-Wittig sequence
摘要:
Dihydropyrimidinone azides 1, obtained from trimethylsilyl chloride-catalyzed Biginelli reaction of 2-azidobenzaldehyde, ethyl acetoacetate, and urea (or thiourea) at room temperature, reacted with triphenylphosphine to give iminophosphorane 2. A tandem aza-Wittig reaction of iminophosphorane 2 with isocyanate, acyl chloride or CS2 in the presence of K2CO3 or NEt3 generated pyrimido[1,6-c]quinazolin-4-ones 4, 6 or 8 in moderate to good yield. (C) 2010 Elsevier Ltd. All rights reserved.