Synthesis of a carbon analogue of scytonemin

Synthetic Access to Cyclopenta[a]inden-2(1H)-ones from Morita-Baylis-Hillman Products of 2-Alkynyl Benzaldehydes

A new strategy for the synthesis of cyclopenta[a]inden-2(1H)-ones has been developed. An intramolecular Pauson-Khand reaction of the Morita-Baylis-Hillman (MBH) adducts, derived from 2-alkynyl benzaldehydes, provided the consequent novel cyclopenta[a]inden-2(1H)-ones bearing multifunctionalities including an ester group at the fused ring junction (tert-carbon center). The generality of this approach was illustrated by studying the several MBH derivatives containing diverse substitutions/functionalities.

Creation of Novel Cyclization Methods Using sp-Hybridized Carbon Units and Syntheses of Bioactive Compounds

Some recent results on the development of new and reliable procedures for the construction of diverse ring systems based on the chemistry of sp-hybridized species, especially allene functionality, are described. This review includes: (i) synthesis of the multi-cyclic skeletons by combination of the π-component of allene with suitable other π-components such as alkyne, alkene, or additional allene under Rh-catalyzed conditions; (ii) synthesis of heterocycles as well as carbocycles by reaction of the sp-hybridized center of allene with some nucleophiles in an endo-mode manner; and (iii) total syntheses of natural products and related compounds from the sp-hybridized starting materials.