Diene syntheses azomethines

Kresze, G., Albrecht, R. Heterocycles by diene synthesis. Dienophilic azomethines and their diene adducts. Ber. 1964, 97,490-493. Albrecht, R., Kresze, G. Heterocycles by diene synthesis. II. N-Carbobutyloxymethylene-p-toluenesulfonamide, a new dienophile for the preparation of pyridine, piperideine, and piperidine derivatives by the Diels-Alder synthesis. Chem. Ber. 1965, 98,1431-1434. 

High-pressure diene synthesis with azomethines... 

Cavaleiro et al. developed methodologies based on cycloaddition transformations of porphyrins leading to the synthesis of compounds like chlorins and bacteriochlorins which have strong absorptions in the visible region near or above 650 nm. The reactive diene and dipolarophile species have been o-quinodimethanes [159], azomethine ylides [160] and nitrones [161]. The 1,3-dipolar cycloaddition approach led to the synthesis of glycoderivatives of the chlorin and bacteriochlorin types (Scheme 45) [162]. 

A soln. of ferr-butyl-N-crotonylideneamine in petroleum ether added at 0-5 during 2 hrs. to a stirred soln. of phosgene in dry petroleum ether, and kept 2 hrs. at 10-20 N-fcrf-butyl-N-(3-chlorobuten-l-yl)carbamyl chloride (Y 96%) heated 2 hrs. at 110° in vacuo until HCl-elimination is complete N-(l,3-buta-dien-l-yl)-N-tcrt-butylcarbamyl chloride (Y 94%). F. e., also reaction with satd. azomethines, s. H. IGefer, Synthesis 1972, 39. 

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