We have established that a cationic rhodium(I)-dppf complex catalyzes isomerizations of allyl propargyl ethers to allenic aldehydes in good yields from room temperature to 40 degrees C. On the other hand, carbonyl migration reactions from allenic aldehydes further proceed to give dienals in good yields at 80 degrees C.
Synthesis of Polysubstituted 2-Iodoindenes via Iodonium-Induced Cyclization of Arylallenes
作者:Charlotte Grandclaudon、Véronique Michelet、Patrick Y. Toullec
DOI:10.1021/acs.orglett.5b03634
日期:2016.2.19
2-iodoindenes. In acetonitrile or nitromethane, electrophilic sources of iodine cations react selectively with the C2–C3 double bond of 1-arylallenes to give, after anti nucleophilic attack of the aromatic ring, 2-iodoindene products in high yields. Variations of the allenic skeletons revealed the high 5-endo selectivity and some competitive pathways of cyclization. Postfunctionalization reactions of the carbon–iodine
Scope and Mechanistic Analysis of the Enantioselective Synthesis of Allenes by Rhodium-Catalyzed Tandem Ylide Formation/[2,3]-Sigmatropic Rearrangement between Donor/Acceptor Carbenoids and Propargylic Alcohols
作者:Zhanjie Li、Vyacheslav Boyarskikh、Jørn H. Hansen、Jochen Autschbach、Djamaladdin G. Musaev、Huw M. L. Davies
DOI:10.1021/ja3061529
日期:2012.9.19
Rhodium-catalyzed reactions of tertiary propargylic alcohols with methyl aryl- and styryldiazoacetates result in tandem reactions, consisting of oxonium ylide formation followed by [2,3]-sigmatropic rearrangement. This process competes favorably with the standard O-H insertion reaction of carbenoids. The resulting allenes are produced with high enantioselectivity (88-98% ee) when the reaction is catalyzed by the
gem-Hydrogenation of an internalalkyne with the aid of [Cp*RuCl]4 as the precatalyst is a highly unorthodox transformation, in which one C atom of the triple bond is transformed into a methylene group, whereas the second C atom gets converted into a rutheniumcarbene. In the case of 1,3-enynes bearing a propargylic steering substituent as the substrates, the reaction occurs regioselectively, giving
Five in one: Catalytic cascadereactions of dienynes catalyzed by cationic rhodium(I)–binap complexes lead to the formation of 1,2‐dihydronaphthalenes, naphthalenes, and 1,4‐dihydronaphthalenes. These cascadereactions involve up to five fundamentally different transformations, including the catalytic enantioselective carboformylation of alkenes with aldehydes or the cycloisomerization of enallenes
Synthesis of Allenyl-Bdan via the Cu(I)-Catalyzed Borylation of Propargylic Alcohols with the Unsymmetric Diboron Reagent (Bpin-Bdan)
作者:Lujia Mao、Chunlei Li、Libo Xiang、Dejun Fu、Wangyang Ma、Qing Ye
DOI:10.1021/acs.joc.9b03319
日期:2020.2.21
The synthesis of allenyl-Bdan has been realized via the Cu(I)-catalyzed borylation of propargylic alcohols. This methodology offers a facile and efficient pathway toward allenyboronates with diverse functional groups due to the simple access to the substrates. The substrates bearing ester groups are well-tolerated in the synthesis of allenyl-Bdan under the Lewis acidic conditions. The structures of