Nitrogen nucleophiles cycloaddition processes

The reaction of 81 with diazomethane is another example of nucleophilic cycloaddition process. Elimination of nitrogen from initially formed triazole 142 leads to aziridine 141. Vinylic fluorine in 81 can be replaced by chlorine using the reaction with ClSi(CH3)3/KF. Alternatively, chloride 143 can be prepared by the reaction of 81 with AlCl3. ... 

The reaction of JV,iV-dimethylhydrazones (1-amino-1-azadienes) and alkenylcarbene complexes mainly produces [3C+2S] cyclopentene derivatives (see Sect. 2.6.4.5). However, a minor product in this reaction is a pyrrole derivative which can be considered as derived from a [4S+1C] cycloaddition process [75]. In this case, the reaction is initiated by the nucleophilic 1,2-addition of the nitrogen lone pair to the metal-carbon double bond followed by cyclisation and... 

A large number of catalytic asymmetric MCR are based on deoxo-bisubstitution reactions of carbonyl compounds such as the Mannich and Strecker reactions in which an oxo-group is displaced by two new cr-bonds, one to a nitrogen atom and one to a carbon atom. Other examples of deoxo-bisubstitutions include tandem processes that involve an initial Knoevenagel condensation followed by either a nucleophilic or a cycloaddition. These processes are characterized by the conversion of a C O-K-bond into two new C-C-cr-bonds and have been termed carba-acetalizations. 

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