The application of cyclic and acyclic enol ethers as electrophiles in cross coupling reactions offers new possibilities for the preparation of functional compounds.
环状和非环状烯醇醚作为亲电试剂在交叉偶联反应中的应用为功能化合物的制备提供了新的可能性。
Carbosilylation of Allenes Catalyzed by Palladium Complexes: A New Efficient Route to Substituted Allylic Silanes
作者:Ming-Yuan Wu、Feng-Yu Yang、Chien-Hong Cheng
DOI:10.1021/jo982307a
日期:1999.4.1
An aromatic or olefinic halide RX (C6H5I, p-CH3COC6H4I, p-NO2C6H4I, p-CH3OC6H4I, o-CH3OC6H4I, m-C2H5OCOC6H4I, (Z)-C2H5OCOCH=CHI, 3-iodocyclopent-2-en-1-one, 1-iodothiophene, 1-iodonaphthalene, 3-bromo-5,5-dimethylcyclohex-2-en-1-one, or alpha-bromostyrene), Bu3SnSiMe3 (2), and 1,1-dimethylallene (3a) undergo three-component coupling reaction in toluene in the presence of Pd(dba)(2) (dba = dibenzylideneacetone) to give an allylic silane (Me)(2)C=C(R)CH2SiMe3 in good to excellent yields. When X = I, the yields are substantially higher than when X = Br or Cl (no reaction). This carbosilylation reaction is highly regioselective, with the R group adding to the middle carbon and the silyl group to the unsubstituted terminal carbon of 3a. Monosubstituted allenes R " CH=C=CH2 (R " = cyclo-C6H11, n-Bu, and Ph) also undergo carbosilylation with PhI and 2, producing R " CH=C(Ph)CH2SiMe3 stereoselectively with Z/E between 98/2 and 80/20. Bulkier organic halides and allenes give products with higher Z/E ratios. Based on known palladium-allene and -allyl chemistry, we propose a mechanism to account for this palladium-catalyzed three-component coupling reaction.
1-phenyl-2-vinyltetramethyldisilane in the absence of a quencher led to dimerization of the siliconcarbon double-bonded intermediate to give cis- and trans-1,1,3,3-tetramethyl-2,4-bis(dimethylphenylsilylmethyl)-1,3-disilacyclobutane in moderate yield. The intermediate produced from 1-phenylethenylpetamethyldisilane reacted with both non-enolizable and enolizable ketones to give silyl-substituted olefins
Regio- and Stereoselective Allylindation of Alkynes Using InBr3 and Allylic Silanes: Synthesis, Characterization, and Application of 1,4-Dienylindiums toward Skipped Dienes
Regioselective anti-allylindation of alkynes was achieved using InBr3 and allylic silanes. Various types of alkynes and allylic silanes were applicable to the present allylindation. This sequential process used the generated 1,4-dienylindiums to establish novel synthetic methods for skipped dienes. The 1,4-dienylindiums were characterized by spectral analysis and treated with I2 to stereoselectively