Enantioselective Reduction of Prochiral Ketones Catalyed by Oxazaborolidine Derived from L-Cystine

Two new chiral oxazaborolidine derivated from L-cystine have been used to catalyze the enantioselective reduction of prochiral ketones and the secondary alcohols are obtained with good to excellent opitical yields.

Synthesis of 2,5-disubstitued benzimidazole using SnCl_2-catalyzed reduction system at room temperature

Stannous chloride dihydrate is used as an efficient catalyst in reductive cyclization of 2-nitro-5- substituted aniline Schiff base leading to stable 2,5-disubstitued benzimidazole derivatives in excellent yields with good purity. It provides a novel method of synthesis of 2,5-disubstitued benzimidazole under reductive system at room temperature.

Synthesis and crystal structure of polyaryl substituted diene derivatives based on the reduction of diphenylacetylene with lithium naphthalenide

The reduction of diphenylacetylene with lithium naphthalenide produced two kinds of intermediates,1 or 2,depending on the ratio of diphenylacetylene to lithium naphthalenide.A series of polyaryl substituted ethylene/diene derivatives were synthesized by reaction of electrophⅡes with the corresponding intermediates produced in situ.All new compounds were fully characterized,and their single crystal structures were determined.

Quasi-periodic Solutions for the Derivative Nonlinear Schrdinger Equation with Finitely Differentiable Nonlinearities

The authors are concerned with a class of derivative nonlinear Schr¨odinger equation iu_t + u_(xx) + i?f(u, ū, ωt)u_x=0,(t, x) ∈ R × [0, π],subject to Dirichlet boundary condition, where the nonlinearity f(z1, z2, ?) is merely finitely differentiable with respect to all variables rather than analytic and quasi-periodically forced in time. By developing a smoothing and approximation theory, the existence of many quasi-periodic solutions of the above equation is proved.

Improved and efficient synthesis of Maxacalcitol

Maxacalcitol,the 22-oxa-derivative of 1a,25-dihydroxyvitamin D3,has been used as an antihyperparathyroidism and antipsoriatic drug.In this paper,an alternative synthetic route has been developed using commercially available vitamin D2as the starting material.In addition,as a key intermediate,the asymmetric synthesis of 20（S）-alcohol 14 with the chiral auxiliary（R-CBS） was described for the first time.This new synthetic route afforded Maxacalcitol with improved overall yield（13.9%） in eleven steps.

Lie Symmetry Analysis and Conservation Laws of a Generalized Time Fractional Foam Drainage Equation

In this paper, a generalized time fractional nonlinear foam drainage equation is investigated by means of the Lie group analysis method. Based on the Riemann–Liouville derivative, the Lie point symmetries and symmetry reductions of the equation are derived, respectively. Furthermore, conservation laws with two kinds of independent variables of the equation are performed by making use of the nonlinear self-adjointness method.