scholarly journals Branch- and Enantioselective Allylic C−H Alkylation Works Well for Almost All Types of α-Alkenes

Author(s):  
Zhong-Sheng Nong ◽  
Ling Zhu ◽  
Tian-Ci Wang ◽  
Lian-Feng Fan ◽  
Pu-Sheng Wang ◽  
...  

Abstract Asymmetric functionalization of alkenes represents one of the most attractive and straightforward methods to achieve precise assembly of molecular complexity from cost-effectiveness and sustainability viewpoints. Although the regio- and enantioselective transformations on the carbon-carbon double bond of alkenes have been extensively studied, those on the allylic C−H bonds of inactivated alkenes remain to be explored. Here, we report a Pd-catalyzed branch- and enantioselective allylic C−H alkylation, capable of accommodating almost all types of α-alkenes that range from feedstocks annually manufactured on million-ton scale to olefins tethering a wide scope of appended functionalities, providing unconventional access to chiral γ,δ-unsaturated amides. Notably, mechanistic studies reveal that the regioselectivity is not only governed by the coordination pattern of nucleophiles but also regulated by the ligational behaviors of ligands, highlighting the importance of the mono-ligation of chiral phosphoramidite ligands in provoking high levels of stereo- and branch-selectivity via a nucleophile-coordination enabled inner-sphere allylation pathway.

Synthesis ◽  
2021 ◽  
Author(s):  
Dmitrii L. Obydennov ◽  
Vyacheslav D. Steben’kov ◽  
Konstantin L. Obydennov ◽  
Sergey A. Usachev ◽  
Vladimir S. Moshkin ◽  
...  

Abstract4-Pyrones bearing electron-donating and electron-withdrawing groups react with nonstabilized azomethine ylides to form pyrano[2,3-c]pyrrolidines in moderate to good yields. The reaction proceeds chemoselectively as a 1,3-dipolar cycloaddition of the azomethine ylide at the carbon–carbon double bond of the pyrone activated by the electron-withdrawing substituent. The reactivity of 4-pyrones toward azomethine ylides was rationalized by computational studies with the use of reactivity indexes. The pyrano[2,3-c]pyrrolidine moiety could be modified, for example by a ring-opening transformation under the action of hydrazine to provide pyrazolyl-substituted pyrrolidines.


1984 ◽  
Vol 49 (7) ◽  
pp. 1300-1302 ◽  
Author(s):  
Mitsuo Komatsu ◽  
Yasuo Yoshida ◽  
Masatoshi Uesaka ◽  
Yoshiki Ohshiro ◽  
Toshio Agawa

ChemInform ◽  
2010 ◽  
Vol 27 (5) ◽  
pp. no-no
Author(s):  
H. TANAKA ◽  
R. KIKUCHI ◽  
M. BABA ◽  
S. TORII

1982 ◽  
Vol 23 (28) ◽  
pp. 2859-2862 ◽  
Author(s):  
Bernard Hanquet ◽  
Mohammed El Borai ◽  
Roger Guilard ◽  
Yves Dusausoy

1970 ◽  
Vol 43 (2) ◽  
pp. 313-321 ◽  
Author(s):  
S. W. Cornell ◽  
J. L. Koenig

Abstract The Raman spectra of cis-1,4-, trans-1,4-, and 3,4-polyisoprene are presented, and the frequencies are classified by configurational structure type. The stretching frequency of the carbon-carbon double bond vibrations are used to describe structure content. Only Raman bands characteristic of total 1,4 content and total vinyl content can be observed. Tentative values of structure content determined by both peak height and peak area are presented for two mixed structure rubbers.


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