Facile Alder-Ene Reactions of Silylallenes Involving an Allenic C(sp<sup>2</sup>)H Bond
作者:Venkata R. Sabbasani、Genping Huang、Yuanzhi Xia、Daesung Lee
DOI:10.1002/chem.201503243
日期:2015.11.23
involving the activation of an allenic C(sp2)H over an allylic C(sp3)Hbond is described. In this ene reaction, the presence of a silyl substituent was found to be critical for the observed reactivity and selectivity since the corresponding alkyl‐substituted allenes show different reaction profiles. Computational studies show that the origin of this unusualreactivity is the lower bond dissociation
Oxidative Dimerization of Silylallenes via Activation of the Allenic C(<i>sp</i><sup>2</sup>)–H Bond Catalyzed by Copper(I) Chloride and <i>N</i>-Hydroxyphthalimide
作者:Venkata R. Sabbasani、Daesung Lee
DOI:10.1021/acs.orglett.5b02433
日期:2015.10.2
Novel oxidativedimerization of silylallenes is described. Treatment of silylallenes with a catalytic amount of copper(I) chloride, a substoichiometric amount of N-hydroxyphthalamide, and a stoichiometric amount of a terminal oxidant diacetoxyiodobenzene afforded head-to-head dimers as the main products. Silyallenes containing a small ring afforded only dimers, whereas as the ring size increased 1
Selectivity Control in Alkylidene Carbene-Mediated C−H Insertion and Allene Formation
作者:Jun-Cheng Zheng、Sang Young Yun、Chunrui Sun、Nam-Kyu Lee、Daesung Lee
DOI:10.1021/jo102180f
日期:2011.2.18
Regioselectivity of alkylidene carbene-mediated C-H insertion was explored utilizing electronic, conformational, steric, and stereoelectronic effects. Relying on these factors, highly regio- and chemoselective carbene insertion reaction of C-H bonds in different environments could be obtained. The observed selectivity clearly indicates that an electronic effect plays a more important role than steric effect. In general, C-H bonds in conformationally rigid cyclic environments are less reactive than those in acyclic systems toward carbene insertion, and in this situation, a competing intermolecular reaction between alkylidene carbene and trimethylsilyldiazomethane led to the formation of allenylsilanes. The formation of allenylsilane becomes more favorable as the concentration of reaction becomes higher, as well as the C-H bonds undergoing insertion becomes electronically and conformationally deactivated.
Alkine und cumulene-XX. Trimethylsilylallene durch retro-en-spaltung von trimethylsilylpropargylethern
作者:Henning Hopf、Elke Naujoks
DOI:10.1016/s0040-4039(00)80162-8
日期:——
Complementary Iron(II)‐Catalyzed Oxidative Transformations of Allenes with Different Oxidants
作者:Venkata R. Sabbasani、Hyunjin Lee、Yuanzhi Xia、Daesung Lee
DOI:10.1002/anie.201510006
日期:2016.1.18
Substituent‐ and oxidant‐dependent transformations of allenes are described. Given the profound influence of the substituent on the reactivity of allenes, the subtle differences in allene structures are manifested in the formation of diverse products when reacted with different electrophiles/oxidants. In general, reactions of nonsilylated allenes involve an allylic cation intermediate by forming a