Paul D. Woodgate

Ruthenium-catalysed ortho vinylation of aromatic ketones with alkynes; unexpected cyclopentaannulation

Abstract Ruthenium-catalysed coupling of aromatic ketones with alkynylsilanes yielded in most cases ortho vinylation adducts in high yield. The predominant stereochemistry of the newly introduced double bond was E in all but a few cases. In contrast, 1-acetylnaphthalene underwent a one-pot insertion–cyclisation sequence yielding cyclopenta[ a ]naphthalene derivatives. A bis acetylene gave both mono and bis insertion products.

Chemistry of the podocarpaceae: LXX. Synthesis and cyclopentaannulation of a diterpenoid chromium carbene complex

A pentacarbonylcarbene chromium complex of the diterpenoid methyl O-methylpodocarpate has been prepared and its reactions with some alkynes have been studied with the aim fo synthesising ring-C aromatic steroids. The use of diphenylacetylene resulted in cyclisation to give steroidal derivatives in moderate yield.

Ent-atisane diterpenes from Euphorbia fidjiana

Abstract The heartwood of the Fijian species Euphorbia fidjiana has yielded seven new ent-14-oxo-atisenes, four ent- atisane-16,17-diols, a 4,5-seco-atisene, and a 3,4-seco- atisene-ent-13[S]-hydroxy-14-oxo-3,4-seco-atis-16-en- 3,4-olide, as well as two chlorinated ent-atisanes which were identified as artifacts. Their structures and relative stereochemistry have been determined by detailed high field NMR studies and from an X-ray structure analysis of ent-13-[S]- hydroxyatis-16-ene-3,14-dione. Their absolute configuration is inferred from an X-ray structure of ent-17-p- bromobenzoyloxy-16α-hydroxyatisan-3-one.

Chemistry of the podocarpaceae: LXXI. Preparation, structure, and reactions of some (arene)tricarbonylchromium(0) complexes. Crystal structure of α-tricarbonyl[8,9,11,12,13,14-η)-methyl podocarpa-8,11,13-trien-19-oate]chromium(0)☆

Abstract Tricarbonyl[8,9,11,12,13,14-η)methyl podocarpa-8,11,13-trien-19-oate]chromium(0) ( 7 ), tricarbonyl[4a,5,6,7,8,8a-η)-1,2,3,4-tetrahydronaphthalene]chromium(0) ( 11 ) and (benzene)tricarbonylchromium(0) ( 10 ) were prepared and examined. Complex 7 was obtained as a mixture of diastereomers, an X-ray structural determination showing that the α-isomer possesses a near eclipsed conformation, in agreement with the conformation in solution deduced from 400 MHz 1 H NMR analysis. Carbonions derived from 1,3-dithiane, 2-methyl-1,3-dithiane and 2-(2,2-dimethoxyethyl)-1,3-dithiane ( 24 ), and the dianion derived from 2,2′-methylenebis-1,3-dithiane ( 27 ) were prepared and brought into reaction with the complexes. Compounds 23 and 33 resulted from regioselective attack on 7 at the site predicted. Treatment with methyl electrophiles of the dithianyl η 5 -intermediate leading to 22 did not give products of acetyl incorporation. Arene lithiation-electrophilic quenching of 7 gave a mixture of compound 6 and its C(14) regioisomer along with the novel ketone 39 and its C(14) regioisomer.

Ruthenium-catalysed ortho alkylation of hydroxyacetophenones; the functionalisation of ring C aromatic diterpenoids

Abstract Ortho C-H bond coupling of some 2-alkoxyacetophenones with olefins catalysed by ruthenium complexes results in a high yield of the ortho alkylated product, providing that a suitable protecting group is employed. No such protection was required for a para-alkoxy group; an activating effect was also observed. Bicyclic and tricyclic analogues react similarly.

Coupling reactions of diterpenoid η2-tetracarbonylmanganese complexes with alkynes

Abstract A number of tetracarbonylmanganese complexes derived from podocarpic acid ( 1 ) have been coupled with acetylene or diphenylacetylene to give steroidal analogues in high yield. Several modes of activating these manganese complexes towards coupling reactions were investigated, including oxidative decarbonylation at room temperature and thermal promotion.

Ent-14[S],16β,17-trihydroxyatisan-3-one and further constituents from Euphorbia fidjiana

Abstract The heartwood of the Fijian species Euphorbia fidjiana has yielded the new compounds ent -14[ S ],16β,17-trihydroxyatisan-3-one, 5-hydroxyethylmellein, and 6-hydroxy-5-methylmellein, and 24 other compounds identified as stigmasterol, β-sitosterol, stigmasterone, β-sitosterone, 3-hydroxystigmastan-6-one, butyrospermol, 24-methylenecycloartan-3β-ol, cycloart-24-en-3β-ol, 3β-hydroxycycloart-25-en-24-one, 24-methylenecycloartan-3-one, cycloart-24-en-3-one, lasiodiplodin, des- O -methyllasiodiplodin, 5-methylmellein, 5-methoxymellein, 5-hydroxy-methylmellein, scopoletin, xanthoxylin, 2,4,6-trimethoxyacetophenone, erythritol, d -mannitol, d -arabitol, β- d -glucose, and α- d -glucose. Lasiodiplodin, des- O -methyllasiodiplodin and the three substituted melleins may be products of fungal infestation of the wood.

Ent-pimarane and ent-abietane diterpenes from Euphorbia fidjiana

Abstract The heartwood of the Fijian species Euphorbia fidjiana has yielded three new ent -pimaren-3-ones, a new ent -abietadienolide, as well as the known compounds jolkinolides A and E. The structures and relative stereochemistry of the ent -pimaren-3-ones have been determined from high field NMR studies. The structures of the γ-lactones were assigned on the basis of NMR data and an X-ray structure analysis. The structures of the previously reported pseudojolkinolides have been revised.

Reactions with alkenes of η2-7-oxotetracarbonylmanganese complexes derived from diterpenoids

Abstract A number of activated 7-oxotetracarbonylmanganese(I) complexes derived from podocarpic acid ( 1 ) and from dehydroabietic acid have been coupled with alkenes to give C(14) functionalised derivatives in high yields. Some coupling reactions resulted in cyclization to C(7), forming 4 H -acephenanthrylene derivatives in moderate yields. Several modes of activating these manganese complexes towards coupling reactions were investigated; these included oxidative decarbonylation at room temperature, thermal promotion, and palladium-mediation.

Reactions of enol acetates with thallium(I) acetate–iodine

The action of thallium(I) acetate and iodine on some enol acetates has been examined as a general method for the formation of α-iodo-ketones.