Synthesis ofgem-Difluorocyclopropa(e)nes and O-, S-, N-, and P-Difluoromethylated Compounds with TMSCF2Br
摘要:
Two-in-one: Me3 SiCF2 Br is an efficient difluorocarbene source and is compatible with both neutral and aqueous basic conditions. Bromide-ion-initiated [2+1] cycloaddition with alkenes/alkynes and hydroxide ion promoted α-addition with (thio)phenols, (thio)alcohols, sulfinates, heterocyclic amines, and H-phosphine oxides give the corresponding gem-difluorinated compounds with broad functional-group tolerance.
Chloride ion-catalyzed generation of difluorocarbene for efficient preparation of gem-difluorinated cyclopropenes and cyclopropanes
作者:Fei Wang、Wei Zhang、Jieming Zhu、Huaifeng Li、Kuo-Wei Huang、Jinbo Hu
DOI:10.1039/c0cc04548a
日期:——
A chloride ion-catalyzed generation of difluorocarbene from a relatively non-toxic and inexpensive precursor, Me(3)SiCF(2)Cl (1), under mild and neutral conditions leads to an efficient preparation of gem-difluorocyclopropenes and difluorocyclopropanes through [2 + 1] cycloaddition reactions with alkynes and alkenes, respectively.
An easy access to 5-fluoropyridazines by a [2 + 1]/[3 + 2]-cycloaddition sequence between terminal alkynes, a difluorocarbene, and a diazo compound is reported. This approach does not necessitate the isolation of any intermediates, and a wide range of novel 5-fluoropyridazines was synthesized from readily available starting materials. Additionally, these compounds were used as a platform to access
Synthesis of gem-Difluorinated Cyclopropanes and Cyclopropenes: Trifluoromethyltrimethylsilane as a Difluorocarbene Source
作者:Fei Wang、Tao Luo、Jinbo Hu、Ying Wang、Hema S. Krishnan、Parag V. Jog、Somesh K. Ganesh、G. K. Surya Prakash、George A. Olah
DOI:10.1002/anie.201101691
日期:2011.7.25
Highly versatile: The Ruppert–Prakash reagent (Me3SiCF3) can be an efficient source of difluorocarbene. By varying the nonmetallic initiator that is used (F− at lower temperatures and I− at higher temperatures), a range of structurally diverse alkenes and alkynes can be converted into the corresponding gem‐difluorinated cyclopropanes and cyclopropenes in good yields (see scheme).
An efficient, straightforward and general method for the de novo synthesis of highlyfunctionalized 4-fluoropyridines was developed via a cooperative copper- and base-catalyzed [3+3] cycloaddition of active methylene isocyanides with difluorocyclopropenes. The resulting 4-fluoropyridines can be readily diversified by various nucleophiles.
Synthesis of bicyclo[3.1.0]hexanes by (3 + 2) annulation of cyclopropenes with aminocyclopropanes
作者:Bastian Muriel、Alec Gagnebin、Jerome Waser
DOI:10.1039/c9sc03790j
日期:——
We report the convergent synthesis of bicyclo[3.1.0]hexanes possessing an all-carbon quaternary center via a (3 + 2) annulation of cyclopropenes with cyclopropylanilines. Using an organic or an iridium photoredox catalyst and blue LED irradiation, good yields were obtained for a broad range of cyclopropene and cyclopropylaniline derivatives. The reaction was highly diastereoselective when using difluorocyclopropenes