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91.
92.
Takuya Shintani 《Tetrahedron letters》2004,45(9):1849-1851
The phenylmenthyl derivative, previously shown to be very effective chiral auxiliaries in the diastereoselective [2+2] photocycloaddition of cyclic enones with the simplest olefin, ethylene, was attached to poly(ethylene glycol)-grafted Wang resin. We then investigated the diastereoselective [2+2] photocycloaddition on solid support in several solvents. As the result, we accomplished good selectivity in toluene as well as the recycle of the polymer-supported chiral auxiliary. This is the first example that bicyclo[4.2.0]octane derivative has been obtained photochemically on the solid support. 相似文献
93.
Shintani R Duan WL Park S Hayashi T 《Chemical communications (Cambridge, England)》2006,(34):3646-3647
A rhodium/binap complex has been found to effectively catalyze the isomerization of unactivated internal alkynes to the corresponding 1,3-dienes in the presence of an azomethine imine as the reaction promoter. 相似文献
94.
Shintani R Okamoto K Otomaru Y Ueyama K Hayashi T 《Journal of the American Chemical Society》2005,127(1):54-55
Catalytic arylative cyclization of alkynals has been developed by the use of phosphine-free rhodium/diene complexes as catalysts. An asymmetric variant of this process has been successfully realized by employing a C2-symmetric chiral bicyclo[2.2.2]octadiene ligand. The rhodium/diene catalyst system is also effective for arylative cyclization of other substrates such as alkynones and enynes, achieving multiple carbon-carbon bond formations in a single step. 相似文献
95.
[reaction: see text] The first catalytic asymmetric synthesis of 2-aryl-2,3-dihydro-4-quinolones has been developed by way of a rhodium-catalyzed 1,4-addition of arylzinc reagents to 4-quinolones. These 1,4-adducts can be obtained with high enantioselectivity by the use of (R)-binap as a ligand, and high yields are realized by conducting the reactions in the presence of chlorotrimethylsilane. 相似文献
96.
97.
Misa Numano Naoto Nagami Soichiro Nakatsuka Takazumi Katayama Kiichi Nakajima Sou Tatsumi Dr. Nobuhiro Yasuda Prof. Dr. Takuji Hatakeyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11574-11577
A demethylative direct borylation is reported, which was applied to the synthesis of benzo[fg]tetracenes containing boronate ester, amide, and thioester substructures. Depending on the heteroatom adjacent to boron, the molecules showed characteristic photophysical properties, molecular arrangements, and chemical stabilities. The key to the successful synthesis is the appropriate choice of the boron source and Brønsted base. The versatility of the direct borylation was demonstrated by the synthesis of a boronate‐based benzo[hi]hexacene. 相似文献
98.
99.
A magnesium enamide derived from N-2-(N′,N′-dimethylamino)ethyl imine reacts with primary and secondary alkyl chlorides and fluorides to give an α-alkylated ketone in good to excellent yields upon hydrolysis of the imine moiety. Reactions of the highly nucleophilic magnesium enamide derived from an unsymmetrical ketone take place regioselectively. In addition, the C-C bond formation is stereospecific: a substantial inversion of stereochemistry at the electrophilic carbon center (Walden inversion) was observed, proving its potential utility for the production of optically active compounds. 相似文献
100.
[reaction: see text] A new synthetic method for chiral organosilicon compounds through a rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to beta-silyl alpha,beta-unsaturated carbonyl compounds has been developed. By employing (R,R)-Bn-bod* as a ligand, a range of arylboronic acids can be coupled with these substrates in very high enantiomeric excess. The resulting beta-silyl 1,4-adducts can be converted to beta-hydroxy carbonyl compounds or allylsilanes while retaining their stereochemical information. 相似文献