Gayle K. Schulte

Group selective reduction of acetals related to the ansa chain of the streptovaricins: Conformational and stereochemical analysis

Abstract The group selective reductive cleavage of benzylidene acetals derived from diols containing chains equipped with a central chirotopic, nonstereogenic carbon atom is reported. The stereochemistry that is obtained at the central carbon is suitable for application to the synthesis of members of the streptovaricin class of antibiotics.

Model studies directed toward the avermectins: a route to the spiroketal subunit

Abstract Oxidative cyclization of a dihydropyran bearing a pendant alcohol is used to synthesize a spiroketal system of the type found in the avermectins.

Cytotoxic cembranoids from the gorgonian Pseudopterogorgia bipinnata

Abstract Four new cytotoxic cembranoids, denoted as bipinnatins a-d, have been isolated from the gorgonian coral Pseudopterogorgia bipinnata . Their structures were determined through a combination of spectroscopic and x-ray crystallographic methods.

Singlet oxygen reactions of 2-carbalkoxy-3-methoxypyrroles.

Abstract The reactions of singlet oxygen with 3-methoxy-2-carbalkoxypyrroles lead to 2,5-oxygenation, 2,3-epoxides, or 2,3-oxidative cleavage, depending on substitution patterns and reaction conditions.

Substrate specificity in enzymatically mediated trans acetylation reactions of calicheamicinone intermediates

Abstract Enzymatically mediated acetylation of racemic 5 leads to enantiomerically homogeneous precursors of calicheamicinone and ent -calicheamicinone.

Synthesis and characterization of pyrrolinone carboxylates formed by reaction of vicinal tricarbonyl derivatives with aldehyde Schiff bases

A series of vicinal trcarbonyl derivatives undergo reaction with aldehyde Schiff bases forming pyrrolinone derivatives by benzilic acid-related rearrangements. The structures were established by X-ray analyses and, independently by the SESAMI NMR-based computer program

Confirmation by total synthesis of the revised structure of sporol : an application of cyclic thionocarbonate-initiated radical cyclization

The revised structure of sporol is confirmed by the synthesis of the racemate. Tri-n-butylstannyl radical induced fragmentation of a thionocarbonate and subsequent cyclization is employed to prepare a key component in the synthesis.

The synthesis of neosporol: A trichothecene in search of a natural product

Abstract The synthesis of neosporol 14, a yet to be discovered trichothecene, is described. The critical reaction is a highly diastereoselective Claisen rearrangement that sets the C5C6 stereochemistry.

EPOXIDES DERIVED FROM PYRANOSYL DIENES : UNUSUALLY STABLE GLYCOSYL DONORS

Abstract A pyranosyl diene appropriately substituted for use in a total synthesis of staurosporine has been synthesized. The mono-epoxides and bis-epoxides obtained from treatment of this diene with dimethyldioxirane are unusually stable.

Benzilic acid rearrangements in the reactions of aryl vicinal tricarbonyl derivatives with aldehyde Schiff bases

Abstract Reactions of aryl and hetero vicinal tricarbonyl derivatives with aldehyde Schiff bases of the general structure RCH2CHO lead to pyrrolinone derivatives by benzilic acid-related rearrangements, driven, most probably, by iminium ion intermediates.