N.N. Girotra

Total synthesis of the macrolide, zearalenone.

Abstract Total synthesis of the biologically active macrolide zearalenone together with its optical resolution and the determination of its absolute configuration as “S” are described. Wittig condensation with an ortho aldehydic ester proceeded in part with vicinal interaction and formation of an acetylenic product.

Synthesis and biological activity of MK 287 (L-680,573): a potent, specific and orally active paf receptor antagonist

Abstract An enantioselective synthesis of MK 287 (L-680,573), a member of a family of trans-,5-diaryltetrahydrofurans, and its biological activity are described.

The total synthesis of (±) compactin and its natural (+) enantiomer

Abstract Total synthesis of (±) compactin 12 and its natural (+) enantiomer has been achieved via a multistep sequence originating from butadiene and p-benzoquinone.

Chemoselective removal and replacement of the C-4′ and C-6 acyl esters of zaragozic Acid A

Abstract An efficient chemical sequence is described for the modification of the C-4′ and C-6 positions of zaragozic acid A. Key reactions include the specific conditions devised for selective removal of either the C-4′ acetate or the C-6 acyl chain. The resultant hydroxy intermediates were then derivatized as esters, ethers, carbamates, and carbonates.

A new route in the sequential total synthesis of compactin

Abstract The synthesis and regioselective hydrogenation of 1,2,6,7,8, 8aβ-hexahydro-8α-hydroxy-2-methylene-1β-naphthaleneacetic acid methyl ester 4a , has provided a novel synthetic pathway to the hypocholesterolemic agent, compactin 9 .

Rearrangement of zaragozic acid a derivatives

Abstract The C 6 mesylate of desacyl zaragozic acid A tris tBu ester has been observed to undergo rearrangement in the presence of CsF in DMF.

The relative configuration of flavipucine

Abstract The relative configuration of the antibiotic flavipucine as inferred from a differential rearrangement reaction was confirmed by ozonolysis to a crystalline oxidoester amide identical with a specimen of this same compound prepared by synthesis.

An alternative synthetic route to compactin via a michael-alkylation sequence

Abstract The cis -octalinone 1 , derived from p-benzoquinone and butadiene, was transformed via a Michael-alkylation sequence to the key triene precursor 5b in a total synthesis of the HMG-CoA reductase inhibitor compactin.

Novel transformations of zaragozic acid A derivatives with cesium fluoride

Abstract C4-Hydroxy protected zaragozic acid A derivatives, upon treatment with CsF in DMF, underwent novel transformations to give tricyclic compounds. The process was initiated by intramolecular C3 proton abstraction by the C7 alkoxide anion to form the enolate ion, which can cyclize by two different pathways.

Halogenation of C16-macrolide antibiotics 17-haloleucomycins (A3)

Abstract The preparation of 17-bromo-, chloro- and fluoroleucomycin A3 is described. Formation of a new cyclic ether was observed on pyrolysis of the 17-bromo system.