New and efficient procedures for the synthesis of stereodefined 2-(hetero)aryl and 2-methyl substituted alkyl 2-alkenoates having very high stereoisomeric purity
摘要:
Stereodefined 2-(hetero)aryl and 2-methyl substituted alkyl 2-alkenoates of general formula 1 and 2 have been synthesized with a high degree of stereoselectivity as well as in good overall yields starting from alkyl 2-alkynoates, 4.
Synthesis of variously 2-substituted alkyl (Z)- and (E)-2-alkenoates and (Z)- and (E)-α-ylidene-γ-butyrolactones via palladium-mediated cross-coupling reactions between organostannanes and organic halides
作者:Fabio Bellina、Adriano Carpita、Massimo De Santis、Renzo Rossi
DOI:10.1016/s0040-4020(01)89314-5
日期:1994.1
2-(1-alkenyl) as well as 2-acyl substituted α,β-unsaturatedesters, is based on the cross-coupling reaction between easily available alkyl (Z)- or (E)-2-halo-2-alkenoates and organostannanes in NMP, in the presence of catalytic amounts of PdCl2(PhCN)2, AsPh3 and CuI. (Z)-and (E)-2-ethenyl substituted α,β-unsaturatedesters prepared according to this procedure have been proven to be useful precursors to (Z)-
Palladium-catalyzed reaction between aryl or alkenyl halides and (1-carbalkoxy-1-alkenyl)zinc iodides. A new class of unmasked β-substituted acrylate α-anion equivalents
β-substituted acrylate α-anion equivalents have been directly and very efficiently prepared by insertion of zinc metal into the carbon-iodine bonds of alkyl (E)- or (Z)-2-iodo-2-alkenoates, (E)-or (Z)-(4), respectively. The stereoisomeric composition of these new reagents, 12, depends on the experimental conditions used for their preparation. Their Pd0-catalyzed reaction with alkenyl or aryl halides
<i>Trans-</i> and <i>Cis-</i>Selective Lewis Acid Catalyzed Hydrogermylation of Alkynes
作者:Todd Schwier、Vladimir Gevorgyan
DOI:10.1021/ol0521026
日期:2005.11.1
[reactions: see text] The first examples of Lewis acid catalyzed hydrogermylation of alkynes have been demonstrated. It was found that this method has much higher functional group compatibility compared to the known Lewis acid catalyzed hydrosilylation and hydrostannation reactions. Remarkably, the stereochemical outcome of this hydrogermylation reaction depends on the nature of the alkyne used: proceeding