Lanthanide Triflate-Catalyzed Preparation of β,β-Difluorohomopropargyl Alcohols in Aqueous Media. Application to the Synthesis of 4,4-Difluoroisochromans
摘要:
An indium-mediated Barbier-type reaction of difluoropropargyl bromide with several aldehydes in aqueous media was enhanced by a catalytic amount of a lanthanide triflate (5 mol %). The reaction gave the corresponding beta,beta-difluorohomopropargyl alcohols with high regioselectivity. The [2 + 2 + 2] alkyne cyclotrimerization of beta,beta-difluorohomopropargyl alcohols with monosubstituted acetylenes produced 4,4-difluoroisochromans in good yields with moderate regioselectivity.
Expedient synthesis of α,α-difluorohomopropargylic alcohols from TIPS-difluorobromopropyne via a Zn-mediated propargylation of aldehydes and ketones
摘要:
The synthesis of alpha,alpha-difluorohomopropargyl alcohols containing an alkynyl silane moiety is reported. The ti tie compound was prepared by the reaction of the organozinc derivative of TIPS-bromodifluoropropyne with aldehydes or ketones under mild conditions and in good yields. (C) 2000 Elsevier Science Ltd. All rights reserved.
Fluorinated Building Blocks. The Discovery of a Stable Difluoroallenyl Indium and the Synthesis of <i>g</i><i>em</i>-Difluoroallenyl and -propargyl Synthons in Aqueous Media
作者:ZhiGang Wang、Gerald B. Hammond
DOI:10.1021/jo000832f
日期:2000.10.1
The synthesis of two highly functional fluorinated motifs, TIPS-C triple bond C-CF2-, and CF2=C=C(TIPS)- is described. This approach is mediated by a room-temperature stable ethereal solution of a difluoroallene indium intermediate. This intermediate may be used as "stock solution" in the reaction with aqueous HCHO, to yield CF2=C=C(TIPS)CH2OH, and in a reaction with a Schiff base to produce the corresponding
描述了两个功能性高的氟化基序TIPS-C三键C-CF2-和CF2 = C = C(TIPS)-的合成。这种方法是由室温稳定的二氟丙烯烯铟中间体的乙醚溶液介导的。该中间体可以在与HCHO水溶液反应中用作“原液”,以产生CF 2 = C = C(TIPS)CH 2 OH,并且在与席夫碱反应中以产生相应的β,β-二氟高炔丙基胺。CF2 = C = C(TIPS)CH2-OH的合成潜力已通过简便有效的5-内-trig环化反应转化为二氟二氢呋喃衍生物得到了证明。通过在主要为水的介质中将铟加到醛和TIPS-C三键C-CF2Br的混合物中,可以合成同炔的宝石二氟醇。
On the Nature of Organoindium Intermediates: the Formation of Readily Isolable Difluoropropargylindium Reagents and their Regioselectivity Towards Electrophilic Substitutions
作者:Bo Xu、Gerald B. Hammond
DOI:10.1002/chem.200801367
日期:2008.11.10
The structure and reactivity of intermediate propargylindium complexes have been investigated. Their reaction with electrophiles produced a difluoroalkyne or -allene, depending on the nature of the electrophiles. A mechanism based on the Curtin-Hammett principle was invoked to explain this phenomenon. A newly proposed mechanism on the formation of indium(III) complexes, through the intermediacy of