1H-1,3-Diazepines, 5H-1,3-diazepines, 1,3-diazepinones, and 2,4-diazabicyclo[3.2.0]heptenes,

Visible light-induced one-pot synthesis of CF3/CF2-substituted cyclobutene derivatives

An efficient one-pot approach for the controllable synthesis of trifluoromethyl/gem-difluoromethylene substituted cyclobutene derivatives has been developed. The mechanism may involve visible light-induced [2+2]-cycloaddition of quinolinones with 1-bromo-1-trifluoromethylethene, followed by base-promoted dehydrobromination, [1,3]-H shift and further dehydrofluorination. A variety of CF3/CF2-substituted cyclobutenes that are currently difficult to obtain are afforded in good yields in this protocol, which may find its way into future fluorinated cyclobutene preparation.

NIS-mediated regioselective amidation of indole with quinazolinone and pyrimidone

A mild, metal-free condition was developed for the direct regioselective C2 amidation of indoles and pyrroles with quinazolinone and pyrimidone derivatives in intermolecular fashion, which led to novel indolyl/pyrrolyl quinazolinone and pyrimidone derivatives in moderate to good yields.

3-Pyridylnitrene, 2- and 4-pyrimidinylcarbenes, 3-quinolylnitrenes, and 4-quinazolinylcarbenes. Interconversion, ring expansion to diazacycloheptatetraenes, ring opening to nitrile ylides, and ring contraction to cyanopyrroles and cyanoindoles

Precursors of 3-pyridylnitrene and 2- and 4-pyrimidinylcarbenes all afford mixtures of 2- and 3-cyanopyrroles on flash vacuum thermolysis, but 3-cyanopyrroles are the first-formed products. 3-Quinolylnitrenes and 4-quinazolinylcarbenes similarly afford 3-cyanoindoles. 2-Pyrimidinylcarbenes rearrange to 3-pyridylnitrenes, but 4-pyrimidinylcarbenes and 4-quinazolinylcarbenes do not necessarily rearrange to the corresponding 3-pyridylnitrenes or 3-quinolylnitrenes. The ring contraction reactions are interpreted in terms of ring opening of either the nitrenes or the diazacycloheptatetraenes to nitrile ylides.

1H-1,3-Diazepines and Ketenimines from Cyanotetrazolopyridines

Cyano-substituted tetrazolo[1,5-a]pyridines/2-azidopyridines 8T and 15T undergo thermal ring opening to the azides 8A and 15A. Solution photolysis causes nitrogen elimination and ring expansion to 1,3-diazacyclohepta-1,2,4,6-tetraenes 10 and 17, which react with alcohols to afford 2-alkoxy-1H-1,3-diazepines, with secondary amines to 2-dialkylamino-5H-1,3-diazepines, and with water to 1,3-diazepin-2-ones (12–14, 19, 21). Argon matrix photolysis of the azides affords the diazacycloheptatetraenes 10 and 17 as principal products together with ring-opened dicyanovinylketenimines 11 and 18. The matrix-isolated species were identified on the basis of comparison of the infrared spectra with those calculated at the B3LYP/6–31+G* level.

1,3-Dipolar character of 2-vinyl quinazoline 3-oxides; first and second generation cycloaddition products

The reaction between the heteroaromatic N-oxides 1a, 1b and 1c with dimethyl acetylenedicarboxylate or methyl propiolate furnishes 1,3-benzodiazepines, the products of ring transformations of primarily formed cycloadducts. The structures of 8a and 10a have been confirmed by X-ray crystallographic analysis. The aldonitrone 1c also reacts with N-methylmaleimide and with phenyl vinyl sulfone to furnish the first examples of primary cycloaddition products from quinazoline 3-oxides.