rhodium(I) by means of an RhI–OH complex, enables the conjugate transfer of nucleophilic silicon onto α,β-unsaturated acceptors. Pre- or in situ formed cationic rhodium(I)–binap complexescatalyze this novel carbon–silicon bond formation with exceptional enantiocontrol, 92 to >99% ee for cyclic carbonyl and carboxylcompounds as well as >99% ee for acyclic carboxylcompounds.
铑(I)催化的硅-硼键活化,即通过Rh I -OH络合物将硅从硼转变为铑(I),可以将亲核硅共轭转移到α,β上-不饱和受体。预制的或原位形成的阳离子铑(I)-联萘酚配合物可催化这种新型的碳-硅键形成,具有出色的对映体控制能力,环状羰基和羧基化合物的ee为92%至> 99%ee,无环羧基化合物的ee> 99%。
Asymmetric Conjugate Silyl Transfer in Iterative Catalytic Sequences: Synthesis of the C7-C16 Fragment of (+)-Neopeltolide
作者:Eduard Hartmann、Martin Oestreich
DOI:10.1002/anie.201002916
日期:2010.8.16
that is not the question! The anti,anti configuration of the C7–C16 fragment of (+)‐neopeltolide is stereoselectively installed in an iterative sequence of catalyst‐controlled Si group and Me group transfers, even with mismatched selectivity in the former (Si=Me2PhSi, see scheme; TBS=tert‐butyldimethylsilyl).
匹配或不匹配,这不是问题!(+)-新油菜碱内酯的C7–C16片段的抗,抗构象被立体选择性地安装在催化剂控制的Si基团和Me基团转移的迭代序列中,即使前者的选择性不匹配(Si = Me 2 PhSi,请参见方案; TBS =叔丁基二甲基甲硅烷基)。
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
Neat mixtures of arene/hetarenecarbaldehydes, alkanals as well as alkenals with alkyl (triphenylphosphoranylidene)acetates react exothermally to furnish the corresponding alkenes. In certain cases, heating has to be provided externally. Reaction times are short and yields are generally very high. Neat mixtures of ketones and alkyl (triphenylphosphoranylidene)acetates react preferentially under microwave irradiation. The better stabilized phosphoranes do not react in the solid state with aldehydes or ketones under conventional heating, but necessitate microwave irradiation, although not all of the phosphoranes have been found to be stable under microwave irradiation at 500 W (2450 MHz).
Practical Synthesis of (E)-α,β-Unsaturated Esters from Aldehydes
作者:Benjamin List、Arno Doehring、Maria T. Hechavarria Fonseca、Kathrin Wobser、Hendrik van Thienen、Ramon Rios Torres、Pedro Llamas Galilea
DOI:10.1002/adsc.200505196
日期:2005.10
Based on a modification of the Doebner–Knoevenagel reaction, a practical and highly efficient synthesis of α,β-unsaturated esters with excellent regio- and stereoselectivity was developed. The reactions are catalyzed by 4-dimethylaminopyridine in DMF at room temperature or below. Both aliphatic and aromatic aldehydes can readily be used in the process.