Selective reductions. 31. Lithium triethylborohydride as an exceptionally powerful nucleophile. A new and remarkably rapid methodology for the hydrogenolysis of alkyl halides under mild conditions
Metalloradical-Catalyzed Selective 1,2-Rh-H Insertion into the Aliphatic Carbon–Carbon Bond of Cyclooctane
摘要:
The selective aliphatic carboncarbon activation of cyclo-octane (c-octane) was achieved via the Rh-II(ttp)-catalyzed 1,2-addition of Rh(ttp)H to give Rh(ttp)(n-octyl) (ttp = tetratolylporphyrinato dianion) in good yield under mild reaction conditions. This mechanism is further supported by DFT calculations. The reaction worked only with the sterically accessible Rh(ttp) porphyrin complex but not with the bulky Rh(tmp) system (tmp = tetrakismesitylporphyrinato dianion), thus showing the highly steric sensitivity of carboncarbon bond activation by transition metal complexes.
A general and convenient copper-mediated trifluoromethylthiolation of primary and secondary alkyl halides was described. Variation of the solvent, additives and time allowed optimization of the reaction. A wide range of alkyl halides were explored to give a set of alkyl trifluoromethyl thioethers in moderate to excellent yields. A variety of functional groups, including ethers, thioether, esters, nitriles, amides, and ketal groups, were well tolerated in the electrophilic partner.
作者:Benjamin A. Haag、Zhi-Guang Zhang、Jin-Shan Li、Paul Knochel
DOI:10.1002/anie.201005319
日期:2010.12.3
Updated classic: Primary and secondary alkylzinc reagents add to various aryldiazonium salts leading regioselectively to polyfunctional indoles by means of a [3,3]‐sigmatropic shift and subsequent aromatization. This organometallic variation of the Fischer indolesynthesis tolerates a wide range of functional groups and displays absolute regioselectivity.
A Photoirradiative Phase-Vanishing Method: Efficient Generation of HBr from Alkanes and Molecular Bromine and Its Use for Subsequent Radical Addition to Terminal Alkenes
phase-vanishing (PV) system comprised of an alkane, perfluorohexanes, and bromine was successfully combined by photoirradiation to efficiently generate hydrogenbromide, which underwent radicaladdition with 1-alkenes in the hydrocarbon layer to afford terminal bromides in high yields.
The direct selective halogenation of unactivated C(sp3)–H bonds into C-halogen bonds was achieved using a nano Ag/AgCl catalyst at RT under visible light or LED irradiation in the presence of an aqueous solution of NaX/HX as a halide source, in air. The halogenation of hydrocarbons provided mono-halide substituted products with 95% selectivity and yields higher than 90%, with the chlorination of toluene
The Synthesis of Chiral Allyl Carbamates via Merger of Photoredox and Nickel Catalysis
作者:Mateusz Garbacz、Sebastian Stecko
DOI:10.1002/adsc.202000404
日期:2020.8.4
A mild, and versatile, organophotoredox/Ni‐mediated protocol was developed for the direct preparation of diverse, enantioenriched allyl carbamates. The reported approach represents a significant departure from classical step‐by‐step synthesis of allyl carbamates. This dual photoredox/Ni based strategy offers unrivalled capacity for convergent unification of readily available alkyl halides and chiral