C(sp)–C(sp<sup>3</sup>) Bond Formation through Cu-Catalyzed Cross-Coupling of<i>N</i>-Tosylhydrazones and Trialkylsilylethynes
作者:Fei Ye、Xiaoshen Ma、Qing Xiao、Huan Li、Yan Zhang、Jianbo Wang
DOI:10.1021/ja3004792
日期:2012.4.4
Copper-catalyzed cross-coupling of N-tosylhydrazones with trialkylsilylethynes leads to the formation of C(sp)-C(sp(3)) bonds. Cu carbene migratory insertion is proposed to play the key role in this transformation.
A matter of catalyst: Azole compounds can be directly alkylated with N‐tosylhydrazones that bear unactivatedalkylgroups (see scheme; phen=1,10‐phenanthroline, Ts=p‐toluenesulfonyl). Nickel catalysis enables the introduction of simple secondary alkyl chains into benzoxazole compounds, whereas the alkylation of 5‐aryloxazoles and benzothiazole is possible by using a cobalt catalyst.
Experimental evidence of a cyclopropylcarbinyl conjugative electronic effect
作者:Phyllis A. Leber、Anthony J. Nocket、Matthew F. Wipperman、Sylvia Zohrabian、Christopher Y. Bemis、Munsha K. Sidhu
DOI:10.1039/c3ob41365a
日期:——
Bicyclo[3.2.0]hept-2-enes undergo thermalrearrangement to norbornenes via diradical transition structures. The synthesis of exo-7-cyclopropylbicyclo[3.2.0]hept-2-ene has been achieved by cycloaddition of cyclopentadiene and cyclopropylketene, generated by treatment of cyclopropylacetyl chloride with triethylamine. A comparison of the cyclopropyl substituent effect with that of other C7 substituents
A visible-light-driven and room temperature photo-Wolff-Kischner reaction of sulfur ylides and N-tosylhydrazones has been developed for the first time to provide modular access to alkene synthesis. The high functional group tolerance and broad substrate scope were demonstrated by more than 60 examples. Both E- and Z-olefinic stereochemistry in the products could be controlled with excellent stereoselectivity
Cyclopropylmethyl Palladium Species from Carbene Migratory Insertion: New Routes to 1,3-Butadienes
作者:Lei Zhou、Fei Ye、Yan Zhang、Jianbo Wang
DOI:10.1021/ol2034405
日期:2012.2.3
Cyclopropylmethyl palladium species can be accessed by Pd-catalyzed reaction of either cyclopropyl N-tosylhydrazone with halide or N-tosylhydrazone with cyclopropyl halide. In both approaches migratory insertion of Pd carbene is the key process. These transformations constitute new approaches toward 1,3-butadiene derivatives.