92269-61-9Relevant articles and documents
Asymmetric Synthesis of Alkylzincs by Rhodium-Catalyzed Enantioselective Arylative Cyclization of 1,6-Enynes with Arylzincs
Chen, Jiahua,Hayashi, Tamio
supporting information, p. 18510 - 18514 (2020/08/21)
A chiral diene-rhodium complex was found to catalyze the reaction of 1,6-enynes with ArZnCl to give high yields of 2-(alkylidene)cyclopentylmethylzincs with high enantioselectivity (95–99 % ee). The enantioenriched alkylzincs were readily converted in a one-pot approach into a wide variety of functionalized products by taking advantage of their unique reactivity. The catalytic cylcle involves arylrhodation of alkyne, intramolecular alkenylrhodation of alkene, and transmetalation of the alkyl-rhodium intermediate into alkylzinc.
Asymmetric Synthesis of Protected Cyclohexenylamines and Cyclohexenols by Rhodium-Catalyzed [2+2+2] Cycloaddition
Masutomi, Koji,Sugiyama, Haruki,Uekusa, Hidehiro,Shibata, Yu,Tanaka, Ken
supporting information, p. 15373 - 15376 (2016/12/03)
It has been established that cationic rhodium(I)/axially chiral biaryl bis(phosphine) complexes catalyze the asymmetric [2+2+2] cycloaddition of 1,6-enynes with electron-rich functionalized alkenes, enamides, and vinyl carboxylates, to produce the corresponding protected cyclohexenylamines and cyclohexenols. Interestingly, regioselectivity depends on structures of substrates. The present cycloaddition was successfully applied to the enantioselective total synthesis of (?)-porosadienone by using the amide moiety as a leaving group.
Rhodium-catalyzed regio-, diastereo-, and enantioselective [2+2+2] cycloaddition of 1,6-enynes with acrylamides
Masutomi, Koji,Sakiyama, Norifumi,Noguchi, Keiichi,Tanaka, Ken
supporting information, p. 13031 - 13035 (2013/03/13)
Transition-metal-catalyzed intermolecular [2+2+2] cycloadditions of a,w-diynes or enynes with unsaturated compounds are valuable methods for the synthesis of complex bicyclic molecules in a single step.[1] For example, the transitionmetal- catalyzed [2+2+2] cycloaddition of 1,6-enynes with alkynes enables the facile preparation of densely substituted annulated cyclohexadienes.[2] In 2005, the groups of Evans and Shibata developed asymmetric variants of this reaction that furnish annulated cyclohexadienes with one stereogenic center by using cationic rhodium(I)/chiral bisphosphine complexes as catalysts (Scheme 1).[3, 4] Additionally, it has been reported that the cationic rhodium(I)/chiral bisphosphine complexes catalyze the asymmetric [2+2+2] cycloaddition of 1,6-diynes with electron-deficient alkenes, to also afford annulated cyclohexadienes with one stereogenic center (Scheme 1).[5] However, the transition-metal-catalyzed [2+2+2] cycloadditions involving two alkene units have been largely limited to the intramolecular reactions of dienynes.[6] Only two examples of the transition-metalcatalyzed intermolecular [2+2+2] cycloaddition involving two alkene units have been reported to date.[7, 8] In 1999, Montgomery and co-workers reported the nickel-catalyzed [2+2+2] cycloaddition of 1,6-enynes with enones.[7] In 2010, Ogoshi et al. reported the nickel-catalyzed [2+2+2] cycloaddition of two enones with alkynes.[8] However, these reactions are limited to enone derivatives and their asymmetric variants have not been realized (Scheme 1). On the other hand, our research group has demonstrated that acrylamide derivatives are highly reactive substrates in cationic rhodium(I)/bisphosphine-catalyzed carbon-carbon bond-forming reactions.[9] Herein, we have achieved the unprecedented catalytic asymmetric [2+2+2] cycloaddition of 1,6-enynes with alkenes by using acrylamides as alkenes and a cationic rhodium(I)/(R)-H8-binap complex as the catalyst.
