The organic reactions in water, as the most significant green solvent, have attracted much attention due to their unique properties over conventional organic ones. In the catalytic area, heteropoly acids (HPAs) are also promising green solid acids to replace environmentally harmful liquid acid catalysts. Herein, we wish to report the organic reactions catalyzed by HPAs, their salt, and polyoxometalates (POMs) in aqueous systems.

The Birch reduction is unique, in synthetic approaches, due to the adaptable substitution patterns of the substituted cyclohexa-1,4-and 1,3-dienes, particularly enol ethers. Birch reduction as a key and sometimes as the only reduction tool has found several applications in total synthesis of several natural occurring compounds. This name reduction is very important and quite useful for reduction of aromatic and none-aromatic moieties. It is particularly useful in aromatic compounds due to its selectivity of reduction of certain double bonds, which are present in one of the starting materials in multi-step total synthesis. It is also applicable when further reduction of nonaromatic moieties as a part of natural product structures, is required. In this report, we try to highlight the applications of this reaction as a key step in the total synthesis of natural products. It covers the applications of Birch reduction in total synthesis of naturally occurring compounds from 2003 till date.

Reactions -[124 refs.]. -(HERAVI, M. M.; VAZIN FARD, M.; FAGHIHI, Z.; Green Chem. Lett. Rev. 6 (2013) 4, 282-300, http://dx.

Review: 119 refs.