New types of composite pericyclic reactions

The review is devoted to 'complex' pericyclic reactions, i.e., multistep one-pot reactions comprising a cascade of pericyclic steps and concerted processes the transition state of which is a superposition of transition states of two pericyclic reactions. A number of characteristic examples of cascade pericyclic processes demonstrating their significance for synthetic practice are given. The greater part of the review concerns reactions with a 'composite' pericyclic transition state, particularly, dyotropic shift, bispericyclic reactions and hiscotropic rearrangements. The attention is focused on detailed analysis of various types of coarctate reactions, which is due to the synthetic significance of many of them and detailed elaboration of their theoretical base as a continuation and further development of the Woodward–Hoffmann theory for spirocyclic conjugated systems. Bibliography — 115 references.