Cycloadditions higher order

C-C Bond Formation (Part 1) by Addition Reactions Higher-order Cycloadditions ... 

This chapter is the first review whose sole focus is only on metal-catalyzed and metal-mediated higher-order cycloaddition reactions where all of the reaction types are discussed. Previous reviews have focused on specific types of higher-order cycloadditions (referenced in individual chapters), on the general topics of metal-mediated and metal-catalyzed cycloaddition reactions,5-8 and on methods for forming medium-sized rings.9... 

Metal-mediated and -catalyzed [3 + 2 + 2]-higher-order cycloaddition reactions have also proved to be viable and mechanistically novel methods for the synthesis of seven-membered rings. The reported [3 + 2 + 2]-cycloadditions of allyliridium (Equation (30)),139 -allylcobalt (Scheme 47),140 and allylmanganese (Equation (31 ))141 complexes with alkynes involve the reaction of preformed allylmetal complexes with two separate alkynes, leading to a cycloheptadiene-metal complex. 

There are two main classes of [4 + 2 + 2]-metal-catalyzed higher-order cycloadditions that have been reported. The first class involves the reaction of 1,3-dienes (the four-carbon component) with norbornadienes (both two-carbon components) and the second involves the reaction of 1,3-dienes with either two alkynes or an alkyne and an alkene as the two-carbon components (Scheme 59). 

---