John V. Turner

Dilithium tetrabromonickelate (II) as a source of soft nucleophilic bromide : Reaction with epoxides

Abstract Dilithium tetrabromonickelate (II) in THF serves as a source of “soft” nucleophilic bromide and reacts regioselectively with epoxides to give bromohydrins in high yield.

A Mild and Versatile Method for Carboxy Group Activation and Esterification

Abstract In his review of recent methods for the esterification and protection of carboxy groups, Haslam notes that a great need still exists for a versatile and simple process whereby esters may be formed under mild conditions.2 It is appropriate, therefore, that we should disclose a straightforward and economical procedure which we have been using for the esterification of labile poly-function natural products, e. g. gibberellins and penicillins, and the preparation of allylic esters of dihydro-aromatic acids.

Stereocontrolled synthesis of gibberellin A19 from gibberellic acid

Abstract The biosynthetically important C-20 gibberellin, gibberellin A 19 5 , has been prepared from the readily obtained C-19 gibberellin, gibberellic acid 8 , by means of an efficient stereocontrolled ten step sequence.

An economical diels-alder strategy for the synthesis of daphniphyllum alkaloids

Abstract A convergent and essentially self-consistent strategy, featuring an unusual Diels-Alder reaction has been devised for the stereo-controlled synthesis of a logical tetracyclic precursor 21 to daphniphyllum alkaloids.

Syntheses of C20 gibberellin A36 and A37 methyl esters from gibberellic acid

Abstract Gibberellic acid 1 has been stereospecifically transformed into the methyl esters of the C 20 gibberellins A 36 4 and A 37 5 through a sequence which features three concurrent reductive processes and a novel oxidative cleavage of a ketone enolate.

Chloroethoxy(trimethyl)silane: A hard-base trap which preserves tms ether groups and improves the wittig methylenation of gibberellins

Abstract A reagent, 2-chloroethoxy(trimethyl)silane (CETS), has been devised which ensures the preservation of TMS ether groups during Wittig methylenation in protic media and which makes this formerly capricious reaction with 16-keto gibberellins a reliable and straightforward procedure.

A highly convergent and flexible strategy for the synthesis of a-ring aromatic steroids

Abstract Using Hendricksons criteria for systematic synthesis design, a strategy featuring a linear six carbon synthon (7) for bis-annulation has been devised for economic, flexible and highly convergent syntheses of A-ring aromatic steroids.

Hybrid Birch-Claisen Methodology for arylation at allylic termini: synthesis of (±)-herbertene

Abstract A hybrid Birch-Claisen methodology has been developed for the regio- and stereo-controlled arylation of allyl groups, and applied to a synthesis of (±)-herbertene.

Preparation of tert-butyldimethylsilyl (tbdms) enol ethers using potassium hydride in the presence of tbdms chloride

Abstract TBDMS enol ethers can be readily prepared regio- and stereoselectively under equilibrating conditions in high yield by adding potassium hydride to a THF solution of ketone with TBDMS chloride in situ .

Stereoselective reduction of 3-keto gibberellin acids to 3β-ols using k-selectride with KH2PO4 buffer

Abstract KH 2 PO 4 , buffered K-Selectride gives with 3-keto gibberellin acids, borates which are reduced stereoselectively to 3β-ols.