ChemInform Abstract: Rh(I)‐Catalyzed CO Gas‐Free Carbonylative Cyclization Reactions of Alkynes with 2‐Bromophenylboronic Acids Using Formaldehyde.

Abstract

Indan derivatives Q 1050Rh (I)-Catalyzed CO Gas-Free Carbonylative Cyclization Reactions of Alkynes with 2-Bromophenylboronic Acids Using Formaldehyde. -Paraformaldehyde is used as an CO source in the reaction to afford various indenones [cf. (IV)]. The ratio of the catalysts is crucial. For unsymmetrical alkynes, a sterically bulky or electron--withdrawing group favors the α-position of the carbonyl carbon in the products. The reaction of 2-bromophenyl(trimethylsilyl)acetylene (XVa) with the non-halogenated boronic acid requires the addition of styrene. The similar reaction for the phenyl or butyl derivatives fails [cf. (IVd), (XVII)]. -(MORIMOTO*, T.; YAMASAKI, K.; HIRANO, A.; TSUTSUMI, K.; KAGAWA, N.; KAKIUCHI, K.; HARADA, Y.; FUKUMOTO, Y.; CHATANI, N.; NISHIOKA, T.; Org.