Heterocyclic synthesis 1,5-dipolar electrocyclization

The generation and reactivity of conjugated azomethine ylides has been reviewed.148 1,3-Dipolar cycloaddition and 1,5- and 1,7-electrocyclizations have been described as powerful strategies for the synthesis of monocyclic and annulated five- and seven-membered nitrogen heterocyclic compounds. 

There is a type of electrocyclic process that is of considerable value for heterocyclic ring synthesis 1,3-dipolar cycloadditions producing five-membered heterocycles. 

There are two types of electrocyclic process which are of considerable value for heterocyclic ring synthesis one of these is 1,3-dipolar cycloaddition, and the second involves a Diels-Alder type addition using some type of azadiene the latter does not in general produce aromatic heterocycles and, important though it is, will not be dealt with here. 

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See also in sourсe #XX -- [ , , , , ]

See also in sourсe #XX -- [ , , , , ]

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