Regioselective C‐2‐H benzylation of quinazolin‐4(3H)‐ones with N‐tosylhydrazones in a ligand dependent copper system was studied. An array of substituted quinazolin‐4(3H)‐ones were coupled effectively with a wide variety of N‐tosylhydrazones derived from aryl ketones to afford the alkylated products in moderate to good yields. This is a useful, time‐efficient, and scalable procedure for the construction
Radical reactions with 3H-quinazolin-4-ones: synthesis of deoxyvasicinone, mackinazolinone, luotonin A, rutaecarpine and tryptanthrin
作者:W. Russell Bowman、Mark R. J. Elsegood、Tobias Stein、George W. Weaver
DOI:10.1039/b614075k
日期:——
Alkyl, aryl, heteroaryl and acyl radicals have been cyclised onto the 2-position of 3H-quinazolin-4-one. The side chains containing the radical precursors were attached to the nitrogen atom in the 3-position. The cyclisations take place by aromatic homolytic substitution hence retain the aromaticity of the 3H-quinazolin-4-one ring. The highest yields were obtained using hexamethylditin to facilitate cyclisation rather than reduction without cyclisation. The alkaloids deoxyvasicinone 2, mackinazolinone 3, tryptanthrin 4, luotonin A 5 and rutaecarpine 8 were synthesised by radical cyclisation onto 3H-quinazolin-4-one.
烷基、芳基、杂芳基和酰基自由基已环化连接到3H-喹唑啉-4-酮的2-位。含有自由基前体的侧链被连接到3-位的氮原子上。环化反应通过芳香均裂取代进行,因此保留了3H-喹唑啉-4-酮环的芳香性。使用六甲基二锡促进环化而不是直接还原而未发生环化,最高产率得以实现。生物碱去氧vasicinone 2、mackinazolinone 3、色胺酮4、luotonin A 5和rutaecarpine 8通过自由基环化反应合成于3H-喹唑啉-4-酮。
Facile access to <i>N</i>-formyl imide as an <i>N</i>-formylating agent for the direct synthesis of <i>N</i>-formamides, benzimidazoles and quinazolinones
N-Formamide synthesis using N-formyl imide with primary and secondary amines with catalytic amounts of p-toluenesulfonic acid monohydrate (TsOH·H2O) is described. This reaction is performed in water without the use of surfactants. Moreover, N-formyl imide is efficiently synthesized using acylamidines with TsOH·H2O in water. In addition, N-formyl imide was successfully used as a carbonyl source in the
The reaction of 3-(2-cyanophenyl)quinazolin-4(3H)-one with various primary alkylamines gave 3-alkylquinazolin-4(3H)-ones via an addition of the nucleophile, ring opening, and ring closure (ANRORC) mechanism. This type of reaction required hydroxy group functionality in either the solvent or reagent. When hydroxylamine was used as nitrogen nucleophile, the intermediate of this reaction was isolated