Mark A. W. Finch

An excellent reagent for the removal of the t-butyldimethylsilyl protecting group

Abstract Aqueous hydrofluoric acid is an excellent reagent for the removal of t -butyldimethylsilyl protecting groups.

New routes to substituted tropones

Abstract We describe the synthesis of various mono- and di-substituted tropones from 8-oxabicyclo[3.2.l]octenones, and also two novel cleavage reactions of these oxabicycles.

Total synthesis of prostaglandin A2 involving the reaction of a heterocuprate reagent with an allyl epoxide

A new route to prostaglandin A2(18) involves as the key step the SN′anti reaction of the allyl epoxide (12) and the cuprate reagent (9).

Synthesis of (±)-6β-prostaglandin I1 and (±)-6β-decarboxyprostaglandin I1

The known hydroxy-aldehyde (5) has been converted into 6β-decarboxyprostaglandin I1(19) and 6β-prostaglandin I1(3) by (i) reaction with an appropriate organometallic reagent, (ii) cyclisation via the intermediate formation of an iodonium ion, and (iii) hydrodeiodination and desilylation.

Synthesis of 9-deoxa-9,10-dehydroprostaglandin-D2 through reaction of 2-oxatricyclo[3.3.0.04,6]oct-7-en-3-one with a cuprate reagent

The prostanoid (10) has been prepared by reaction of the tricyclic lactone (4) with the cuprate reagent (12) to give the acid (5) and subsequent Cope rearrangement of the related aldehyde (6).

Total synthesis of (±)-6β-prostaglandin I1

(±)-6β-Prostaglandin I1(3) has been prepared from the readily available unsaturated aldehyde (6) in four steps.

Preparation and some reactions of 2-oxatricyclo[3.3.0.0]oct-7-en-3-one : synthesis of 9-deoxa-9,10-dehydroprostaglandin D2

The tricyclic lactone (1) was prepared by two methods. Reaction of (1) with electrophilic reagents occurred on the more exposed exo-face of the alkene unit resulting in the formation of the epoxylactone (8) on peracid oxidation and the bromolactones (9)–(11) on bromination in the appropriate solvent. Thiophenoxide ion reacted with (1) in SN2 fashion to give the acid (13) while deuteriation studies suggested that lithium dibutylcuprate reacted with (1) through the SN′ pathway preferentially to give the acid (15). The cuprate reagent (20) reacted with the lactone (1) to form the acid (21) which was converted into the prostanoid (29) in a standard fashion.

SN′ reactions involving organocuprate reagents

The allyl halides (1) and (14) and the allyl epoxide (5) react with butylcuprate reagents through an SN′anti process preferentially: with the same reagents the hindered halide (10) gives the product derived from an SN′syn reaction.

Rearrangements of aryl-8-oxabicyclo[3.2.1]octenones: synthesis of novel biaryls and 1-aryl-3-furylpropanones

The formation of 3-arylbenzaldehydes through rearrangement of 3-aryl-8-oxabicyclo[3.2.1]oct-2-en-7-ones is reported, together with various rearrangement reactions of 2-aryl-8-oxabicyclo[3.2.]oct-6-en-3-ones, and a novel approach to the natural product acamelin.

Synthesis of prostaglandin A2 through reaction of 3-endo-bromotricyclo[3.2.0.0]heptan-6-one with a cuprate reagent

The bromo-ketone (4) reacted with the cuprate reagent (2) to give the norbornanone (5). Two ways of converting the ketone (5) into the unsaturated lactone (8) were discovered. The lactone (8) was converted into the hydroxyaldehyde (9)en route to 9-deoxa-9,10-didehydroprostaglandin D2(10) and into prostaglandin A2(12)via the γ-lactone (11).