79909-76-5Relevant academic research and scientific papers
Highly versatile enantioselective conjugate addition of grignard reagents to α,β-unsaturated thioesters
Ruiz, Beatriz Macia,Geurts, Koen,Fernandez-Ibanez, M. Angeles,Horst, Bjoern Ter,Minnaard, Adriaan J.,Feringa, Ben L.
, p. 5123 - 5126 (2008/03/28)
Herein, we report efficient catalysts for the asymmetric copper-catalyzed conjugate addition of Grignard reagents to α,β-unsaturated thioesters. MeMgBr adds to aromatic α,β-unsaturated thioesters with excellent enantioselectivities and moderate to good yi
Catalytic asymmetric synthesis of acyclic arrays by tandem 1,4-addition-aldol reactions
Howell, Gareth P.,Fletcher, Stephen P.,Geurts, Koen,Ter Horst, Bjorn,Feringa, Ben L.
, p. 14977 - 14985 (2008/02/04)
Herein, we report efficient acyclic stereocontrol in tandem 1,4-addition-aldol reactions triggered by catalytic asymmetric organometallic addition. Grignard reagents add to α,β-unsaturated thioesters in a 1,4-fashion and the resulting magnesium enolates are trapped with aromatic or aliphatic aldehydes. The process provides a range of tandem products bearing three contiguous stereocenters with excellent control of relative and absolute stereochemistry. The various diastereomeric products have been fully characterized using single-crystal X-ray analysis and the origins of stereocontrol in this tandem protocol are discussed. The versatility and efficiency of this methodology are demonstrated in the first catalytic asymmetric synthesis of (-)-phaseolinic acid with 54% overall yield via a short and concise route.
Polarized Ketene Dithioacetals. 28. A New General Highly Stereoselective and Regiospecific Method for Homologation of Ketones to α,β-Unsaturated Esters via α-Oxoketene Dithioacetals
Myrboh, Bekington,Ila, Hiriyakkanavar,Junjappa, Hiriyakkanavar
, p. 5327 - 5332 (2007/10/02)
A new highly stereoselective and regiospecific general method for the conversion of active methylene ketones to α,β-unsaturated O-methyl esters, S-methyl esters, and aldehydes via the corresponding oxoketene dithioacetals has been developed.Thus the carbinols 7a-g obtained by sodium borohydride reduction of the corresponding oxoketene dithioacetals 6a-g, derived from acetophenones and their higher homologues, have been shown to undergo boron trifluoride etherate assisted methanolysis to give the corresponding (E)-methylcinnamates 3a-d and their α-alkyl derivatives 3e-g in high yields.Also the acetals 6h-k derived from alkylmethyl ketones gave the corresponding (E)-methylcrotonates 3h-k.Similarly, the acetals 6l-p derived from alicyclic ketones gave the corresponding cyclic ene esters 3l-p under identical conditions.A few carbinols, 7a-d, were shown to undergo partial hydrolysis in the presence of boron trifluoride etherate/water to give the corresponding S-methyl thiocinnamates 8a-d.The cyclic acetals 6l-n were also similarly converted to the corresponding cyclic S-methylene thio esters 8e-g.The (methylthio)alkenyl ketones 20a-d and 18 after borohydride reduction and acidic hydrolysis gave the corresponding (E)-α,β-unsaturated aldehydes 22a-d and 19.The mechanism governing these transformations has been proposed.
The Synthesis of 5-Alkylidenefuran-2(5H)-ones
Babidge, Peter J.,Massy-Westropp, Ralph A.
, p. 1745 - 1756 (2007/10/02)
5-Alkylidenefuran-2(5H)-ones can be synthesized efficiently from S-methyl 5-oxo-2,5-dihydro-furanylidenealkanethioates by treatment with Raney nickel.The ylidenealkanethioates are prepared from the Wittig reactions between cyclic anhydrides and (methylthi
