نتایج جستجو برای: cascade reaction
تعداد نتایج: 454248 فیلتر نتایج به سال:
A detailed kinetic study of the endo-selective epoxide-opening cascade reaction of a diepoxy alcohol in neutral water was undertaken using (1)H NMR spectroscopy. The observation of monoepoxide intermediates resulting from initial endo and exo cyclization indicated that the cascade proceeds via a stepwise mechanism rather than through a concerted one. Independent synthesis and cyclization of the...
The 12C(α,γ)^16O reaction plays a fundamental role in astrophysics and needs to be known with accuracy better than 10%. Cascade γ transitions through the excited states of 16 O are contributing to the uncertainty. We constrained the contribution of the 0+ (6.05 MeV) and 3- (6.13 MeV) cascade transitions by measuring the asymptotic normalization coefficients for these states using the α-transfer...
An approach to the intramolecular Diels-Alder reaction has led to a cascade synthesis of complex carbocycles composed of three fused rings and up to five stereocenters with complete stereocontrol. Computational analysis reveals that the reaction proceeds by a Michael/Michael/cyclopropanation/epimerization cascade in which size and coordination of the counterion is key.
A highly enantioselective dearomative cascade reaction between 2-isocyanoethylindoles and 3-alkenyl-oxindoles was realized using a chiral N,N'-dioxide-Mg(II) complex catalyst. This reaction provides a straightforward access to polycyclic 3-spirooxindoles bearing cyclopenta[b]indole units with four contiguous stereocenters in excellent yields and moderate to good stereoselectivities via a Michae...
A one-pot, multistep reaction cascade to cyclopentenes from alpha,beta-unsaturated ketones and propargylated carbon acids through a combination of organocatalysis and transition metal ion catalysis is reported; the reaction cascade is simple to perform, occurs under mild conditions and is broad in scope.
A powerful cascade reaction was developed for the synthesis of chromeno[4,3-b]pyrrolidines with high yields and excellent stereoselectivities. This efficient cascade reaction expeditiously established two fused rings which bear three contiguous stereogenic centers including one quaternary stereocenter in a single operation with low catalyst loading under mild conditions.
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