Asymmetric addition of aryloxy ethynyl lithium derivatives to N-sulfinyl imines
Aryloxy ethynyl lithium species can be generated in diethyl ether and efficiently added to aliphatic and aromatic N-sulfinyl imines in THF, affording aryloxypropargyl sulfinamides in good yield, and in most cases high diastereoselectivity. The diastereose
Chiral Br?nsted Acid Catalyzed Enantioconvergent Propargylic Substitution Reaction of Racemic Secondary Propargylic Alcohols with Thiols
Despite the significant progress of the enantioselective reaction using chiral catalysts, the enantioselective nucleophilic substitution reaction at the chiral sp3-hybridized carbon atom of a racemic electrophile has not been largely explored. Herein, we report the enantioconvergent propargylic substitution reaction of racemic propargylic alcohols with thiols using chiral bis-phosphoric acid as the chiral Br?nsted acid catalyst. The substitution products were formed in high yields with high enantioselectivities in most cases. The cation-stabilizing effect of the sulfur functional group introduced at the alkynyl terminus is the key to achieving the efficient enantioconvergent process, in which chiral information originating from not only the racemic stereogenic center but also the formed contact ion pair is completely eliminated from the present system.
Alkynoxy-directed C-H functionalizations: Palladium(0)-catalyzed annulations of alkynyl aryl ethers with alkynes
Palladium(0)-catalyzed insertion/annulation sequence between aryl silylethynyl ethers and internal alkynes was found to proceed through activation of ortho-C-H bonds assisted by alkynoxy groups and gave stereoselectively (Z)-2-silylmethylenechromenes. The
Palladium-catalyzed cycloaddition of alkynyl aryl ethers to allenes to form a 2,3-bismethylidene-2,3-dihydro-4h-1-benzopyran framework
Palladium-catalyzed cycloaddition of alkynyl aryl ethers to allenes proceeds through o-CH activation to give 2,3-dihydro- 4H-1-benzopyran derivatives containing 2,3-exo-double bonds. These benzopyran derivatives further cycloadd stereoselectively to dieno
Minami, Yasunori,Kanda, Mayuko,Hiyama, Tamejiro
supporting information
p. 181 - 183
(2014/03/21)
An Ireland-Claisen rearrangement/RCM based approach for the construction of the EF-ring of ciguatoxin 3C
The EF-ring of ciguatoxin 3C, a marine toxin from the dinoflagellate Gambierdiscus toxicus, was stereoselectively synthesized by iterative use of a cyclic ether formation process based on chirality-transferring Ireland-Claisen rearrangement and ring-closing olefin metathesis.
Rhodium-catalyzed complete regioselective lntermolecular cross-cyclotrimerization of aryl ethynyl ethers and nitriles or isocyanates at room temperature
Chemical Equation Presented We have established that a catlonic rhodium(I)/H8- BINAP complex catalyzes the complete regioselective intermolecular cross-cyclotrimerizatlon of aryl ethynyl ethers and nitriles or isocyanates leading to 2,4-diaryloxypyrldines or 4,6-diaryloxy-2-pyridones at room temperature.
Komine, Yoshiyuki,Tanaka, Ken
supporting information; experimental part
p. 1312 - 1315
(2010/06/15)
Gold catalysis: Switching the pathway of the furan-yne cyclization
Changing tracks: By the use of alkynyl ethers as directing elements, the furan-yne cyclization enters a new reaction pathway. Instead of phenols, tetracycles containing two heteroatoms and two new stereocenters are formed (see scheme).
Hashmi, A. Stephen K.,Rudolph, Matthias,Huck, Juergen,Frey, Wolfgang,Bats, Jan W.,Hamzic, Melissa
supporting information; experimental part
p. 5848 - 5852
(2009/12/06)
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