Shashikumar K. Paknikar

A convenient one-pot synthesis of 4-methyl-3-phenyl-, 3-aryl- and 3-aryl-4-phenylcoumarins

Thermal condensation of 2′-hydroxyacetophenones 1a–e with phenylacetic acid 2a in refluxing diphenyl ether gives 4-methyl-3-phenylcoumarins 3a–e. Similarly, reaction of 2-hydroxybenzaldehydes 1f–m and 2-hydroxybenzo-phenones 1n–p with phenylacetic acids 2a–d gives the corresponding 3-arylcoumarins 3f–m and 3-aryl-4-phenylcoumarins 3n–p respectively. Formation of esters 4 and 5 and benzofuran 6 is also observed.

4-Hydroxy-5-methylcoumarin derivatives from Diospyros kaki thunb and D. kaki var. sylvestris makino ; structure and synthesis of 11-methylgerberinol

Two 4-hydroxy-5-methylcoumarin derivatives have been isolated from the roots of Diospyros kaki Thunb and D. kaki Thunb var. sylvestris Makino. One was shown to be identical to gerberinol, previously isolated from the Compositae plant Gerbera lanuginosa. The other was found to be a new natural product whose structure, 11-methylgerberinol, was proved by spectral analysis and further confirmed by synthesis.

p-Menthan-lα,2β4β-triol—Revised Structure of Mullilam Diol: A Constituent of Zanthoxylum rhetsa DC

ABSTRACT A crystalline compound obtained from the oil of Zanthoxylum rhetsa, called mullilam diol and formulated as p-menthane-2,3-dihydroxy-1,4-oxide has been conclusively verified to possess a revised structure, (±)-p-menthan-1α,2β,4β-triol.

Revised structure and stereochemistry of jatamansic acid

Abstract The structure ofjatamansic acid has been revised from 2D-NMR data, an INADEQUATE experiment and X-ray diffraction analysis. The stereochemistry was con

Biomimetic Synthesis and Absolute Configuration of (−)-Tanzanene

Abstract Biomimetic synthesis of (−)-tanzanene (1) from (−)-alloaromadendrene (4) is reported. This first synthesis of (−)-tanzanene also established its absolute configuration as shown in 1.

Santonic acid: Zn–HCl–ether reduction and ceric ammonium nitrate oxidation

Reduction of santonic acid using Zn–HCl–ether yielded succinic anhydride derivatives via pinacolisation followed by rearrangement, whereas oxidation of santonic acid using ceric ammonium nitrate afforded five oxidative decarboxylation products. Dedicated to Prof. TBH McMurry.

Sodium metaperiodate oxidation of isocarvacrol

Sodium metaperiodate oxidation of isocarvacrol 8, a monoterpene phenol has been found to give hydrothymoquinone 13, a natural product and a ring cleavage product 7-oxo-5-isopropyloct-3-en-2,5-olide 14.