Cationic Rhodium(I)‐Catalyzed Carbonylative [2+2+1] Cycloaddition of Diynes

Cationic Rhodium(I)-Catalyzed Asymmetric Cyclohydroformylation of 1,6-Enynes with Formaldehyde

We report a rhodium(I)-catalyzed asymmetric cyclohydroformylation reaction of 1,6-enynes with formaldehyde. The reaction of 1,6-enynes with formaldehyde in the presence of a cationic Rh(I) catalyst, such as [Rh(cod)₂ ]⁺ OTf^- , and a chiral biaryl diphosphine led to asymmetric cyclohydroformylation to produce aldehydes with higher-order structures highly enantioselectively. This transformation procedure is applicable to a variety of enynes, with wide compatibility in various atoms liking between the alkyne and alkene parts, substituents at the alkyne terminus, and substituents at the alkene part, being converted to newly formed aldehydes in 14% to 90% yields with 50% to 98% ee. The products were further transformed with various nucleophiles to alcohols, an amine, and a diene without loss of chirality at their γ-position.

Photodissociation of the Product from a Transition-Metal Center Allows the Catalytic Cycle to Proceed: The Rhodium(I)-Catalyzed [2+2+1] Carbonylative Cycloaddition of Diynes

We describe the effective rhodium(I)-catalyzed [2+2+1] carbonylative cycloaddition of diynes, yielding cyclopentadienes (CPDs), under photoirradiation. The catalysis involves the promotion of the photodissociation of the product CPD, with the simultaneous production of an essential vacant coordination site on the rhodium for an unreacted substrate. The combined use of cationic [Rh(cod)₂]BF₄ as a catalyst and photoirradiation was also found to give various CPDs in high yields (≤96%).

Cobalt-catalyzed carbonylative cycloaddition of substituted diynes to access complexed polycyclic compounds

A cobalt-catalyzed domino Pauson–Khand and [4 + 2] cycloaddition of substituted diynes has been developed for the rapid construction of complexed polycyclic ring systems.