Elusive metastable orthorhombic paracetamol single crystals were obtained by specially designed seeding technique from conventional slow evaporation method. Seeds were prepared at optimized conditions under different cooling rates from seed preparation unit and Powder x-ray diffraction (PXRD) was performed to ensure the polymorphic form of seeds. Saturated paracetamol solutions with three diffe...

The first catalytic asymmetric Fischer indolization is reported. In the presence of a 5 mol % loading of a novel spirocyclic chiral phosphoric acid, 4-substituted cyclohexanone-derived phenylhydrazones undergo a highly enantioselective indolization. Efficient catalyst turnover was achieved by the addition of a weakly acidic cation exchange resin, which removes the generated ammonia. The reactio...

Isotope exchange studies at chemical equilibrium with cyclohexanol and cyclohexanone as reactants show that horse liver alcohol dehydrogenase has a partly random kinetic mechanism, in which the pathway involving nucleotides as first substrate and last product predominates. The exchange studies show clearly, however, that the nucleotides can dissociate from the central complexes at finite rates....

Two new monoterpene indole alkaloids, characterized by previously unencountered natural product skeletons, viz., arborisidine (1), incorporating indolizidine and cyclohexanone moieties fused to an indole unit, and arbornamine (2), incorporating an unprecedented 6/5/6/5/6 "arbornane" skeleton (distinct from the eburnan or tacaman skeleton), were isolated from a Malayan Kopsia arborea. The struct...

Cycloheximide (1) and actiphenol (2) have been isolated from numerous Streptomyces species. Cloning, sequencing, and characterization of a gene cluster from Streptomyces sp. YIM65141 now establish that 1 and 2 production is governed by single biosynthetic machinery. Biosynthesis of 1 features an acyltransferase-less type I polyketide synthase to construct its carbon backbone but may proceed via...