Engineering of Saccharomyces cerevisiae for the production of (+)-ambrein.

The triterpenoid (+)-ambrein is the major component of ambergris, a coprolite of the sperm whale that can only be rarely found on shores. Upon oxidative degradation of (+)-ambrein, several fragrance molecules are formed, amongst them (-)-ambrox, one of the highest valued compounds in the perfume industry. In order to generate a Saccharomyces cerevisiae whole-cell biocatalyst for the production of (+)-ambrein, intracellular supply of the squalene was enhanced by overexpression of two central enzymes in the mevalonate and sterol biosynthesis pathway, namely the N-terminally truncated 3-hydroxy-3-methylglutaryl-CoA reductase 1 (tHMG) and the squalene synthase (ERG9).

Whole-cell (+)-ambrein production in the yeast .

The triterpenoid (+)-ambrein is a natural precursor for (-)-ambrox, which constitutes one of the most sought-after fragrances and fixatives for the perfume industry. (+)-Ambrein is a major component of ambergris, an intestinal excretion of sperm whales that is found only serendipitously. Thus, the demand for (-)-ambrox is currently mainly met by chemical synthesis.

A Versatile and High-Yield Route to Active and Well-Defined Catalysts [Ru(bisphosphane)(H)(solvent) ](BF ).

Simple and efficient: Protonation of [Ru(1,2:5,6-η-cod)(η -cot)] (cod=1,5-cyclooctadiene, cot=1,3,5-cyclooctatriene) with HBF ⋅Et O and then reaction with chiral bisphosphane ligands ($_{\rm PP}^{\frown }$=Me-DuPHOS, BINAP, Tol-BINAP, JOSIPHOS) affords the corresponding [Ru($_{\rm PP}^{\frown }$)(H)(η -cot)] or [Ru($_{\rm PP}^{\frown }$)(1,2,3,4,5-η-C H ')] (C H '=2,4-cyclooctadienyl; see scheme). Exposure of these cations to H in solvents (sol) such as acetone, methanol, and THF affords [Ru($_{\rm PP}^{\frown }$)(H)(sol) ] , which are catalysts for (amongst other things) enantioselective hydrogenations of alkenes.