Peter B. Hitchcock

A Synthesis of (+)- Prelog-Djerassi Lactonic Acid

A new approach to the synthesis of Prelog-Djerassi Lactonic acid (1) is reported. A key step in this synthesis involves an Ireland-Claisen rearrangement/silicon-mediated fragmentation sequence to provide the carbon framework in (1

Synthesis of substituted oligothiophenes and X-ray crystal structures of3′-methyl-2,2′∶5′,2″-terthiophene,3,3″-dimethyl-2,2′∶5′,2″-terthiophene and5′-(2-thienyl)-2,2′∶3′,2″-terthiophene

A range of substituted oligothiophenes has been prepared and characterised. Crystal structures were determined for three substituted terthiophenes. Both in solution and in the solid state, syn-conformers were found to be populated to a greater extent than expected.

The stereochemistry of the 1,2-addition of Grignard reagents to some steroidal unsaturated ketones

The stereochemistry of 3β,17β-dihydroxy-3α-ethylandrost-4-ene, 3α,17β-dihydroxy-3β-methylestr-4-ene and 3β-acetoxy-7α,17β-dihydroxy-7β-methylandrost-5-ene, which were obtained by Grignard reactions from the corresponding αβ-unsaturated ketones, have been established by X-ray crystallography.

The biotransformation of the diterpenoid, rosenonolactone by Mucor plumbeus

The biotransformation of rosenonolactone by the fungus, Mucor plumbeus involves hydroxylation at C-2α C-6β C-12α and epoxidation of the Δ15-alkene.

The Stereochemistry of Epoxidation of Steroidal 4,6-Dienes

The epoxidation of some androsta-4,6-dienes with m-chloroperbenzoic acid has been shown to give the 4β,5β;6α,7α-diepoxides, the stereochemistry can be rationalized in terms of the directing effect of one epoxide on the facial selectivity of the second epoxidation.

Synthetic, structural and theoretical studies on new aromatic 1,2,4-azadiphosphole ring systems: crystal and molecular structure of P2C2But2NPh

Two different synthetic routes to the new aromatic 1,2,4-aza-diphosphole ring system P2C2Bu(t)2NR (R = Pr(i), Pr, Ph, MeC6H4, Bu(t)CH2 and cyclohexyl) are presented and the planar structure of P2C2Bu(t)2NPh, established by a single crystal X-ray diffraction study, is in good agreement with theoretical calculations at the B3LYP/6-311G* level on the parent P2C2H2NH ring.

Isatin chloride: a phantom. Reactions of 2-(2,2-dichloro-2,3-dihydro-3-oxoindol-1-yl)-3H-indol-3-one

It is shown that 2-chloro-3H-indol-3-one 1 and analogues have never actually been isolated and that their reactions, reported over 115 years in 40 papers and 4 patents, are those of more or less impure 2-(2,2-dichloro-2,3-dihydro-3-oxoindol-1-yl)-3H-indol-3-one 14. Several reactions of the parent compound and its 5,5′-dimethyl and 5,5′-dibromo derivatives are reported, especially a reaction with dry methanol leading to the known indoloquinazoline 25 (‘methylisatoid’) and to the known alkaloid tryptanthrin 21 via a photolabile orthoester.

The preparation and crystal structure of 16-acetylandrosta-4,16-dien-3-one

Dehydroisoandrosterone was formylated at C-16 by a Vilsmeier reaction and by condensation with methyl formate. The product of the latter reaction was converted to 16-acetylandrosta-4,16-dien-3-one and its X-ray crystal structure was determined.

The hydroboration of steroidal vinyl halides

The hydroboration of 2- and 3-dibromo and dichioromethylene 5α-androstanes has been shown to afford the 2β-and 3α- and 3β-hydroxymethyl-5α-androstanes respectively; a 3-chloro substituent changed both the regio- and stereochemistry of the hydroboration of a 3,5-diene.

Interactions between the aldehyde and anhydride groups in the diterpenoid fujenal

Methanolysis of the diterpenoid aldehyde:anhydride, fujenal, catalysed by tetracyanoethylene afforded C-6:C-7 methoxylactones whilst the addition of methyl magnesium bromide to fujenal afforded a 6,7-lactone but with an cis A/B ring junction; the structures of these products were established by X-ray crystallography.