100611-76-5Relevant academic research and scientific papers
Catalytic Cyclooligomerization of Enones with Three Methylene Equivalents
Farley, Conner M.,Zhou, You-Yun,Banka, Nishit,Uyeda, Christopher
supporting information, p. 12710 - 12714 (2018/10/09)
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.
Cleavage of Carbon-Carbon Bonds with High Stereochemical Control. 7. Chiral α-Silyl Benzoylcycloalkanes Undergo Base-Catalysed Cleavage with Retention of Configuration When Not Sterically Congested
Paquette, Leo A.,Maynard, George D.,Ra, Choon Sup,Hoppe, Manfred
, p. 1408 - 1418 (2007/10/02)
The cyclic phenyl ketone (-)-1 has been prepared in a manner that allows definition of its absolute configuration.On being heated with sodium and potassium amide in benzene, (-)-1 undergoes C-C bond cleavage with outstanding (96-98percent) levels of configurational retention.This conclusion required interconversion of (-)-1-(trimethylsilyl)-3-isopropylidenecyclopentane (2) with (S)-(-)-3-(trimethylsilyl)cyclopentene (3).The racemic ketones 21, 22, 36, and 37 have also been synthesized and subjected to the Haller-Bauer process.In each case, the resultant cyclic silanes were demonstrated to arise by virtually exclusive stereochemical retention.In the case of 28, an example where the benzoyl carbonyl group is sterically shielded, desilylation was the kinetically dominant reaction with these bases.These results are interpreted on the basis of initial α-silyl carbanion formation within a solvent shell that also encases benzamide.The benefits derived from these special solvational features are predicted not to be useful for extending stereocontrol to targets requiring the operation of intermediate energy-demanding steps.
