Rhodium, selectivity substituted benzenes

Intermolecular cyclization of diyne with monoynes or intermolecular cyclization of triynes is a general method for the synthesis of substituted benzenes [51]. But a serious drawback of this reaction is the presence of a secondary process of diyne dimerization or monoyne trimerization. The selectivity and yield of the cyclic products strongly depend on the structure of the reactants, solvent, catalyst, etc. A highly efficient and selective [2-I-2-I-2] cyclization of diynes and monoynes was described. A rhodium catalyst allowed the reaction to proceed at room... 

The system using the trimethylphosphine-substituted rhodium(I) complex RhCl(CO)(PMe3)2 has been studied in more detail. The photocarbonylation of benzene at 1 atm of CO in the presence of this complex gives benzaldehyde, along with other carbonylation products such as benzyl alcohol and benzophenone. Alkanes can also be photocarbonylated to aldehydes under mild conditions in the presence of RhCl(CO)(PMe3)2 with a high selectivity for carbonylation at the terminal position ... 

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