Alcohols........................................................................................VI

The retrosynthesis involves the following transformations i) isomerisation of the endocyclic doble bond to the exo position ii) substitution of the terminal methylene group by a more stable carbonyl group (retro-Wittig reaction) iii) nucleophilic retro-Michael addition iv) reductive allylic rearrangement v) dealkylation of tertiary alcohol vi) homolytic cleavage and functionalisation vii) dehydroiodination viii) conversion of ethynyl ketone to carboxylic acid derivative ix) homolytic cleavage and functionalisation x) 3-bromo-debutylation xi) conversion of vinyl trimethylstannane to methyl 2-oxocyclopentanecarboxylate (67). 

As early as 1903 Marie and Bunel (22) have shown that alcohols accelerate the persulphate decomposition. Kolthoff, Meehan, and Carr (23) confirmed this and proved that this reaction is not between persulphate ion and alcohol, but between the sulphate ion radical and the alcohol (VI). 

We have noted previously that the catalytic effect of the hydrolytic enzyme chymotrypsin depends critically on the interaction of a hydroxyl and an imidazole group placed in juxtaposition in the enzyme molecule. It was, therefore, particularly tempting to see if an analogous interaction could enhance the catalytic efficiency of PVI, by using copolymers of 4(5)-vinylimidazole with p-vinylphenol (VI/VP) or with vinyl alcohol (VI/VA)... 

Figure 6 Hydrogenation of crotonaldehyde on 5%Ir/Ti02. Crotyl alcohol vi crotonaldehyde mole fractions.

A very useful reagent for the preparation of esters and particularly of nucleoside pyrophosphates is dicyclohexylcarbodiimide (DCC). Its mechanism of action has been studied by Smith et al and is shown in Fig. I. On reaction of DCC (I) with a monophosphate (II) an intermediate believed to have structure (III) is formed. With another molecule of monophosphate (II) a symmetrical pyrophosphate (IV) is formed together with dicyclohexyl urea (V). The reaction can be carried out in a partially aqueous solution because water is a poor nucleophilic agent as compared with the phosphate anion. If the reaction mixture contains excess of an alcohol (VI)... 

---