Synthhesis of new 5 and 6-exomethylenic arachidonic acid analogs.

Are Alkyne Reductions Chemo-, Regio-, and Stereoselective Enough To Provide Pure (Z)-Olefins in Polyfunctionalized Bioactive Molecules?

“…Good chemoselectivity was observed. A methylene exocylic 468 or a terminal double bond, 449 but also isolated (E)olefins 443 and conjugated (Z)-enynes, 120 are compatible with P2−Ni semihydrogenation of a triple bond.…”

An Alkyne Strategy for the Asymmetric Synthesis of Natural Products: Application to (+)‐Spirolaxine Methyl Ether

“…A second ProPhenol‐catalyzed asymmetric alkynylation was employed to set the stereochemistry of the distal stereogenic center and to construct the carbon skeleton (Scheme ). Catalyst‐controlled diastereoselective alkynylation of enal 4 with 4,4‐diethoxybut‐1‐yne21 gave access to the desired propargylic alcohol 9 without disturbing the relatively sensitive phthalide group. The diastereomeric ratio and absolute configuration of this new stereocenter were determined by formation of the methyl mandelate ester (see the http://www.wiley-vch.de/contents/jc_2002/2007/z702637_s.pdf).…”

An Alkyne Strategy for the Asymmetric Synthesis of Natural Products: Application to (+)‐Spirolaxine Methyl Ether

“…A second ProPhenol‐catalyzed asymmetric alkynylation was employed to set the stereochemistry of the distal stereogenic center and to construct the carbon skeleton (Scheme ). Catalyst‐controlled diastereoselective alkynylation of enal 4 with 4,4‐diethoxybut‐1‐yne21 gave access to the desired propargylic alcohol 9 without disturbing the relatively sensitive phthalide group. The diastereomeric ratio and absolute configuration of this new stereocenter were determined by formation of the methyl mandelate ester (see the http://www.wiley-vch.de/contents/jc_2001/2007/z702637_s.pdf).…”