Reactions of the Lithium Salts of the Tribenzylidenemethane Dianion, Diphenylacetone Dianion, and Related Compounds
摘要:
Potentially synthetically useful reactions of the dilithium salts of the title dianions have been investigated, Electrophilic quenching with a variety of reagents usually leads to the expected products in good yield. Quenching the diphenylacetone dianion with 1 equiv of trimethylchlorosilane, however, gives a good yield of 1,3-diphenylallene obtained by formal elimination of a trimethylsiloxy anion from an intermediate monoquenched monoanion salt. NMR studies, however, do not reveal the intermediacy of the 1,3-diphenyl-2-(trimethylsiloxy)allyl anion but rather suggest that the initial reaction site is at carbon, rather than oxygen, Oxidation of the dianions leads either to ring closure or dimerization for the tribenzylidenemethane dianion and to dimerization for the diphenylacetone dianion. The dimerization reactions are stereospecific, both with respect to the two new stereocenters produced and for the double bonds of the bis-silyl enol ether products if the dimeric bis-enolate dianion products are quenched with trimethylchlorosilane.
Nickel-Catalyzed Direct Coupling of Allylic Alcohols with Organoboron Reagents
作者:Gaonan Wang、Yi Gan、Yuanhong Liu
DOI:10.1002/cjoc.201800237
日期:2018.10
The direct coupling of allylicalcohols with arylboronic acids or their derivatives catalyzed by Ni(cod)2 in the presence of a catalytic amount of base has been developed. A wide variety of allylic substrates or arylboronic acids turned out to be applicable to this catalytic system. The present method does not require the use of ligands for stabilizing the nickel catalyst in most cases or additional
Pd(OAc)<sub>2</sub>/P(<i><sup>c</sup></i>C<sub>6</sub>H<sub>11</sub>)<sub>3</sub>-Catalyzed Allylation of Aryl Halides with Homoallyl Alcohols via Retro-Allylation
fashion via a conformationally regulated six-membered cyclic transition state, the allylation reactions are highly regio- and stereospecific when homoallyl alcohols having a substituted allyl group are used. Whereas triarylphosphine is known to serve as a ligand for the palladium-catalyzed allyl transfer reactions, tricyclohexylphosphine proves to significantly expand the scopes of aryl halides to electron-rich
One‐Shot Radical Cross Coupling Between Benzyl Alcohols and Alkenyl Halides Using Ni/Ti/Mn System
作者:Takuya Suga、Yuuki Takahashi、Yutaka Ukaji
DOI:10.1002/adsc.202000945
日期:2020.12.22
A “one‐shot” cross coupling between benzyl alcohols and alkenylhalides has been established. A combination of low‐valent Ti‐mediated C−OH homolysis and the prominent chemistry of Ni‐based radical catalysis afforded the desired cross‐coupled product with good efficiency. The reaction proceeded regardless of the electronic property of benzyl alcohols, and Ar−B bond remained intact throughout the reaction
Xantphos as an Efficient Ligand for Palladium-Catalyzed Cross-Coupling Reactions of Aryl Bromides and Triflates with Allyl Acetates and Indium
作者:Dong Seomoon、Phil Ho Lee
DOI:10.1021/jo702279t
日期:2008.2.1
Xantphos was found to be an efficient ligand for palladium-catalyzed allyl cross-coupling reactions of arylbromides and triflates with allylindium reagents generated in situ from allyl acetates and indium. These reactions occur in high yield with good functional group tolerance.
Nickel-Catalyzed Arylative Ring-Opening of 3-Methylenecycloalkane-1,1-dicarboxylates
作者:Yuto Sumida、Hideki Yorimitsu、Koichiro Oshima
DOI:10.1021/ol100599c
日期:2010.5.21
An arylative ring-opening reaction of cyclic allylmalonates with arylzinc reagents under nickel catalysis has been developed. Upon the ring-opening sp(3)C-sp(3)C bond cleavage, the allylic moiety serves as an allylic electrophile to react with arylzinc reagents. Simultaneously, the malonate moiety is converted to the corresponding zinc enolate, which can react further with electrophiles. The overall process increases molecular complexity and diversity starting from readily available substrates and is useful in organic synthesis.