Asymmetric CuH-catalyzed hydrosilylations en route to the C-9 epimer of amphidinoketide iota.

The C-9 diastereomer of amphidinoketide I has been synthesized. An asymmetric CuH-catalyzed hydrosilylation based on the Solvias nonracemic Josiphos-related ligand (R,S)-PPF-P(t-Bu)2 was successfully used to introduce each of three stereocenters found in the target compound.

Enhancing regiocontrol in carboaluminations of terminal alkynes. Application to the one-pot synthesis of coenzyme Q10.

Two new "generations" of methodological advances are reported for the Negishi carboalumination of terminal alkynes. Use of simple, inexpensive additives that alter the Al-Zr complex formed between Me(3)Al and Cp(2)ZrCl(2) give rise to an especially effective reagent mix that results in virtually complete control of regiochemistry upon carboalumination of 1-alkynes. One timely application to coenzyme Q10 is highlighted.

Asymmetric 1,4-hydrosilylations of alpha,beta-unsaturated esters.

Complexing catalytic amounts of CuH with a nonracemic JOSIPHOS or SEGPHOS ligand, together with stoichiometric PMHS, leads to exceedingly efficient and highly enantioselective 1,4-reductions of beta,beta-disubstituted enoates and lactones. An unprecedented substrate-to-ligand ratio of 7700:1 for this type of reaction is documented.

Asymmetric 1,4-reductions of hindered beta-substituted cycloalkenones using catalytic SEGPHOS-ligated CuH.

The reagent combination of catalytic amounts of copper hydride ligated by a nonracemic SEGPHOS ligand leads in situ to an extremely reactive species capable of effecting asymmetric hydrosilylations of conjugated cyclic enones in very high ees. An unprecedented substrate-to-ligand ratio as high as 275 000:1 for this transformation has been documented. [reaction: see text]