Various α-sulfonylcarbanions have been shown to react at low temperature with di- or tri-halogenolithiocarbenoïds, to give 1-mono- or 1,1-di-halogenoalkenes. Bromocarbenoïds gave better results than their chloro-analogues. Reaction of di-bromolithiomethane with α-lithiated sulfones gives a high yield of vinylic bromides, the stereochemistry of which is cleanly E. Evidence is presented that the carbenoïd
Efficient preparation of trisubstituted alkenes using the SmI2 modification of the Julia–Lythgoe olefination of ketones and aldehydes
作者:István E Markó、Fiona Murphy、Lucien Kumps、Ali Ates、Roland Touillaux、Donald Craig、Santiago Carballares、Simon Dolan
DOI:10.1016/s0040-4020(01)00079-5
日期:2001.3
High yields of di- and tri-substituted alkenes are obtained by a modification of the Julia–Lythgoeolefination reaction involving the in situ capture of intermediate β-alkoxy-sulfones by benzoyl or trimethylsilyl chloride, followed by SmI2-mediated reductiveelimination. This novel protocol also provides a connective preparation of dienyl ethers, which are important partners in Diels–Alder cycloadditions
Synthesis of functionalized cyclic enamines from lithium alkylphenyl sulfones and<i>N</i>-carbo-<i>tert</i>-butoxy lactams
作者:Luis A. Arias、David Arbelo、Arnaldo Alzérreca、José A. Prieto
DOI:10.1002/jhet.5570380104
日期:2001.1
pyrro-lidine or piperidine derivatives 1 in good to moderate yields. The lithium alkyl sulfones 4 are first reacted with the desired protected lactams and then subjected to acidic methanolysis to afford the unusual enam-ines 1a-e. NMR studies (COSY 1H-1H, COSY 1H-13C, NOE) showed the Z enamines to exist in a dynamic equilibrium with the corresponding imines 2. The stereochemistry of the described compounds
Mn-mediated reductive C(sp3)–Si coupling of activated secondary alkyl bromides with chlorosilanes
作者:Liangliang Qi、Xiaobo Pang、Kai Yin、Qiu-Quan Pan、Xiao-Xue Wei、Xing-Zhong Shu
DOI:10.1016/j.cclet.2022.03.070
日期:2022.12
solution to address this problem, but it typically relies on organometallic species. Herein, we report an Mn-mediated reductive C(sp3)–Si coupling to synthesize these compounds from alkyl and silyl electrophiles. This approach avoids the requirement for activation of Si–Cl by transition metals and thus allows for the coupling of various common chlorosilanes. The reaction proceeds under mild conditions