Investigation of Functionalized α-Chloroalkyllithiums for a Stereospecific Reagent-Controlled Homologation Approach to the Analgesic Alkaloid (−)-Epibatidine
作者:Christopher R. Emerson、Lev N. Zakharov、Paul R. Blakemore
DOI:10.1002/chem.201302511
日期:2013.11.25
respectively; α‐deuterated isotopomers D‐18 a and D‐18 d gave yields of 33 and 79 % for the same reaction. Double StReCH of 17 was pursued to target contiguous stereodiads appropriate for the totalsynthesis of (−)‐epibatidine (15). One‐pot double StReCH of boronate 17 by two exposures to (S)‐D‐18 a (≤66 % ee), followed by work‐up with KOOH, gave the expected stereodiad product in 16 % yield (d.r.∼67:33)
bearing 2,9-diaryl-1,10-phenanthroline ligands exhibit not only unprecedented catalytic activity but also unusual ligand-controlled divergent regioselectivity in hydrosilylation reactions of various alkynes. The hydrosilylation protocol described herein provides a highly efficient method for preparing useful di- and trisubstituted olefins on a relatively large scale under mild conditions, and its use
Geminal bis(silanes) are versatile synthetic building blocks owing to their stability and propensity to undergo a variety of transformations. However, the scarcity of catalytic methods for their synthesis limits their structural diversity and thus their utility for further applications. Herein we report a new method for synthesis of geminal bis(silanes) by means of iron-catalyzed dihydrosilylation
phosphine ligands, a Pd-catalyzed asymmetric double hydroxycarbonylation of terminal alkynes to chiralsuccinicacids was achieved in a one-pot manner. The alkyne carbonylation was dictated by the achiral monophosphine to afford branched acrylic acids, while the resulting intermediates further underwent Pd/chiral bisphosphine-catalyzed enantioselective hydroxycarbonylation.