[6+2]Cycloadditions catalyzed by titanium complexes

Progress in the Construction of Cyclooctanoid Systems: New Approaches and Applications to Natural Product Syntheses

“…In addition to photochemical and thermal additions, catalyzed [6 + 2]-cycloadditions have also been successful in accessing eight-membered rings. Reaction between CHT and bis(trimethylsilyl)acetylene, in the presence of titanium catalyst, led to the adduct 54 bearing an eight-membered ring within its bicyclo[4.2.1]nonane framework, Scheme .…”

New in the Catalytic Synthesis of Practically Important Eight- and Nine-Membered Carbocycles by Cycloaddition Reactions with the Participation of 1,3,5-Cycloheptatrienes and 1,3,5,7-Cyclooctatetraenes

“…In the literature, there are preferably publications devoted to the study of reactions of thermally and photochemically induced cycloaddition of alkenes, 1,2-, 1,3-dienes and alkynes to Fe-, Ru-and Cr-containing carbonyl complexes CHT [10][11][12][13][14]. The catalytic variants of these transformations are represented by Ti-, Co-, Cr-, Mo-and Rh-catalyzed cyclodimerization of CHT [15][16][17][18][19][20][21].…”

Ruthenium-Catalyzed [2 + 2] versus Homo Diels–Alder [2 + 2 + 2] Cycloadditions of Norbornadiene and Disubstituted Alkynes: A DFT Study

“…NBD’s inherent ring strain and dual-faced nature can be exploited for the facile establishment of multiple stereocenters in a single reaction by way of face-selective olefin chemistry (Scheme , 2 ) − or ring-opening reactions (Scheme , 9 and 7 ). − Of particular interest are transition-metal-catalyzed cycloadditions, as they are among the most powerful and frequently used methods for the construction of ring systems . Recent developments in transition-metal-catalyzed [2 + 1], [2 + 2] (Scheme , 8 ), − [2 + 2 + 1] (Scheme , 5 ), − [2 + 3] (Scheme , 4 ), − [2 + 2 + 2 + 2] (Scheme , 3 ), − and [2 + 2 + 6] (Scheme , 6 ) reactions have provided efficient methods for the production of 3–8 membered rings.…”