Diastereoselective conjugate addition of 1-enoyl-5-substituted hydantoins with allyltrimethylsilane in the presence of Ti(IV) chloride proceeded to give the corresponding allyl adducts in high yield and high diastereoselectivity. In order to determine the absolute configuration on the β-position of the acyl group, the hydantoin was removed by hydrolysis of the allyl adducts with a base to give ...

We consider the task of filtering the noise from images and other types of inputs which are assumed to be piecewise continuous and piecewise monotone. We show that nonlinear diffusion of the data, a powerful filtering method, is too restrictive for such a case, leading to piecewise constant functions. We claim that the piecewise monotonicity can be enhanced by nonlinear diffusion of first parti...

Hydantoin racemase from Sinorhizobium meliloti was functionally expressed in Escherichia coli. The native form of the enzyme was a homotetramer with a molecular mass of 100 kDa. The optimum temperature and pH for the enzyme were 40 degrees C and 8.5, respectively. The enzyme showed a slight preference for hydantoins with short rather than long aliphatic side chains or those with aromatic rings....

The crystal structure of the title compound, C(15)H(17)BrN(2)O(4)S, is stabilized by inter-molecular N-H⋯O hydrogen bonds which link the mol-ecules into centrosymmetric dimers. The dihedral angle subtended by the 4-bromo-phenyl group with the mean plane passing through the hydantoin unit is 83.29 (5)°. The cyclo-hexyl group adopts an ideal chair conformation with the methyl group in an equatori...

An enantioselective Friedel–Crafts reaction with aliphatic ketimines generated in situ from hemiaminal ethers catalyzed by a chiral Brønsted acid was investigated. The reaction of 2-methoxyfuran with (thio) hydantoin-derived hemiaminal methyl ether proceeded under the influence of a chiral phosphoric acid catalyst to afford the corresponding adduct possessing a quaternary stereogenic center in ...