Catalytic Cyclooligomerization of Enones with Three Methylene Equivalents
Cyclic structures are highly represented in organic molecules, motivating a wealth of catalytic methods targeting their synthesis. Among the various ring-forming processes, cyclooligomerization reactions possess several attractive features but require addressing a unique challenge associated with controlling ring-size selectivity. Here we describe the catalytic reductive cocyclooligomerization of an enone and three carbene equivalents to generate a cyclopentane, a process that constitutes a formal [2 + 1 + 1 + 1]-cycloaddition. The reaction is promoted by a (quinox)Ni catalyst and uses CH2Cl2/Zn as the C1 component. Mechanistic studies are consistent with a metallacycle-based pathway, featuring sequential migratory insertions of multiple carbene equivalents to yield cycloalkanes larger than cyclopropanes.
Farley, Conner M.,Zhou, You-Yun,Banka, Nishit,Uyeda, Christopher
supporting information
p. 12710 - 12714
(2018/10/09)
Pd-catalyzed asymmetric aza-Wacker-type cyclization reaction of olefinic tosylamides
The Pd-catalyzed asymmetric aza-Wacker-type cyclization reaction of the olefinic tosylamides with molecular oxygen as the green oxidant was developed. Under the optimized conditions, excellent catalytic activity and good enantioselectivity with up to 74%
Jiang, Feng,Wu, Zhengxing,Zhang, Wanbin
scheme or table
p. 5124 - 5126
(2010/11/16)
Pd(II)/tBu-quinolineoxazoline: An Air-Stable and modular chiral catalyst system for enantioselective oxidative cascade cyclization
[Chemical Equation Presented] An air-stable and structurally tunable chiral tBu-quinolineoxazoline/Pd(II) catalyst system has been developed for the enantioselective oxidative cascade cyclization of a variety of disubstituted olefinic substrates, with the apparent advantages of good yields and excellent enantioselectivities (up to 98% ee) and diastereoselectivities (dr >24:1). A transition-state model has also been proposed to account for the excellent stereocontrol.
He, Wei,Yip, Kai-Tai,Zhu, Nian-Yong,Yang, Dan
supporting information; experimental part
p. 5626 - 5628
(2010/03/02)
Palladium(II)-catalyzed enantioselective aerobic dialkoxylation of 2-propenyl phenols: A pronounced effect of copper additives on enantioselectivity
A direct O2-coupled Pd(II)-catalyzed enantioselective dialkoxylation of 2-propenylphenols has been developed by utilizing chiral quinoline oxazoline ligands. A detrimental effect of added copper salts on enantioselectivity was observed which is attributed to the displacement of the chiral ligand off of Pd(II). Copyright
Zhang, Yang,Sigman, Matthew S.
p. 3076 - 3077
(2008/04/18)
Steric effects of the ligand in the enantioselective palladium-catalyzed allylic alkylation using chiral oxazolinylpyridines
Eight new chiral oxazolinylpyridines were prepared and assessed in the enantioselective palladium-catalyzed allylic substitution of 1,3- diphenylprop-2-enyl acetate with dimethyl malonate. Catalytic activity and enantioselectivity were found to be highly
Chelucci, Giorgio,Medici, Serenella,Saba, Antonio
p. 543 - 550
(2007/10/03)
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