34136-19-1Relevant articles and documents
Free radical reactions to generate alkenes and/or ionic reactions to generate hydroximoyl chlorides when β-nitrostyrenes react with triethylaluminium or diethylaluminium chloride
Chu, Cheng-Ming,Liu, Ju-Tsung,Lin, Wen-Wei,Yao, Ching-Fa
, p. 47 - 52 (1999)
β-Nitrostyrenes 1 react with triethylaluminium or diethylaluminium chloride in diethyl ether solution and under nitrogen or argon to generate the alkenes 2 and the hydroximoyl chlorides 3 after work-up with ice-cold, cone, hydrochloric acid. The formation of the alkenes 2 is proposed to be a free-radical reaction via NO2/alkyl substitution since the yields of the alkenes 2 are increased in the presence of benzoyl peroxide (Bz2O2) and decreased in the presence of galvinoxyl. Only the alkenes 2 are produced with a high stereoselectivity for the E isomers when β-nitrostyrenes react with triethylaluminium in the presence of one to two equivalents of Bz2O2 as free-radical initiator. The mechanism of the generation of the hydroximoyl chlorides 3 is proposed to proceed through a 1,4-addition pathway to produce nitronates A, then the protonated nitronates B or the nitroso cations C are trapped by chloride ion to form the final products. The yields of compounds 3 are also improved by the presence of Lewis acids such as MgCl2. Medium to high yields of the hydroximoyl chlorides 3 and traces or low yields of the alkenes 2 are generated when triethylaluminium or diethylaluminium chloride react with β-nitrostyrenes in the presence of three equivalents of MgCl2 under argon.
Enzymatic Primary Amination of Benzylic and Allylic C(sp3)-H Bonds
Jia, Zhi-Jun,Gao, Shilong,Arnold, Frances H.
supporting information, p. 10279 - 10283 (2020/07/27)
Aliphatic primary amines are prevalent in natural products, pharmaceuticals, and functional materials. While a plethora of processes are reported for their synthesis, methods that directly install a free amine group into C(sp3)-H bonds remain unprecedented. Here, we report a set of new-to-nature enzymes that catalyze the direct primary amination of C(sp3)-H bonds with excellent chemo-, regio-, and enantioselectivity, using a readily available hydroxylamine derivative as the nitrogen source. Directed evolution of genetically encoded cytochrome P411 enzymes (P450s whose Cys axial ligand to the heme iron has been replaced with Ser) generated variants that selectively functionalize benzylic and allylic C-H bonds, affording a broad scope of enantioenriched primary amines. This biocatalytic process is efficient and selective (up to 3930 TTN and 96percent ee), and can be performed on preparative scale.
Free-Radical Reactions of Trialkylboranes with β-Nitrostyrenes to Generate Alkenes
Yao, Ching-Fa,Chu, Cheng-Ming,Liu, Ju-Tsung
, p. 719 - 722 (2007/10/03)
β-Nitrostyrenes 1 react with trialkylboranes under a nitrogen atmosphere to generate high yields of alkenes 2. The mechanism is proposed to be a free-radical reaction via NO2/alkyl substitution since the reaction is stimulated by the presence of a trace of oxygen in the nitrogen or tert-butyl peroxide or by photolysis and is retarded or inhibited by the addition of galvinoxyl to the solution.
Polylithiumorganic compounds -19. Regioselective carbon-carbon σ-bond scission followed by a 1,6-proton shift upon the reductive metalation of benzylidenecyclopropane derivatives with lithium metal
Maercker, Adalbert,Daub, Volker E. E.
, p. 2439 - 2458 (2007/10/02)
Depending on the substituent α-substituted benzylidenecyclopropanes (32) react more or less readily with lithium dust (2% sodium) in diethyl ether whereby a regioselective scission of only the cyclopropane σ-bond cis to the phenyl ring takes place. Upon raising the temperature the primarily formed 1,3-dilithiumorganic compound due to an agostic interaction rearranges by a 1,6-proton shift into a doubly bridged 1,4-dilithio compound. With α-methylbenzylidenecyclopropane (32c) this rearrangement was shown to occur intermolecularly via a trilithiumorganic compound 56. The suggested mechanism of these reductive metalation reactions via a bisected radical anion 87 where the lithium is mainly bound to the cyclopropyl carbon atom and oriented syn to the phenyl ring, was supported by MNDO (geometries) and ab initio (energies) calculations.
