Hamish C. S. Wood

Specific enzyme inhibitors in vitamin biosynthesis. Part II. Revised structures for some 8-substituted pyrido[2,3-d]pyrimidines

The structures assigned to some 8-substituted pyrido[2,3-d]pyrimidines in an earlier paper have been re-examined. These compounds were synthesised as potential competitive inhibitors of the enzyme riboflavin synthetase. Data from enzyme inhibition studies suggested that the original structures had been wrongly assigned. This was confirmed by studies of nuclear Overhauser effects and by photochemical degradation of the compounds.

Amidinoacetamides in the synthesis of pyrimidines, imidazoles, and purines

2-(Substituted amidino)acetamides and their 2-phenylazo-derivatives were cyclised with one-carbon-atom reagents to the corresponding pyrimidin-4(3H)-ones, identified by unambiguous synthesis from 4,6-dichloropyrimidine and by conversion into the corresponding 9-substituted hypoxanthines. The cyclisation of 2-(substituted amidino)-2-formamidoacetamide formate and hydrochloride salts to the isomeric ring and exocyclic N-substituted aminoimidazolecarboxamides was studied. The imidazolecarboxamides were converted, where possible, into the 3- or 9-substituted hypoxanthines.

Formation of 1,1-dimethylallyl derivatives by reaction of 3,3-dimethylallyl halides with copper(II) chelates of acetylacetone and methyl acetoacetate

Alkylation of the copper(II) chelates of acetylacetone and methyl acetoacetate by 3,3-dimethylallyl halides yields both 3,3-dimethylallyl and 1,1-dimethylallyl products. Formation of 1,1-dimethylallyl derivatives of these β-polyketide analogues appears to be the results of a direct C-alkylation, and is a significant characteristic of the copper chelate reactions, which has not been observed previously with other alkylation reactions of β-diketones or β-keto-esters.

Phosphate esters. Part 3. Formation of sesquiterpene hydrocarbons from cis,trans- and trans,trans-farnesyl diphenyl phosphates

Decomposition of cis,trans- and trans,trans-farnesyl diphenyl phosphates gives mixtures of both acyclic and cyclic sesquiterpene hydrocarbons consisting of β-farnesene, cis-and trans-α-farnesenes, and cis-α- and trans-α-, β-, and γ-bisabolenes, together with small quantities of trans-nerolidol and bisabolol. The proportion of the cyclic hydrocarbons was greater from the cis,trans-farnesyl diphenyl phosphate. Solvolysis of geranyl chloride gives linalool and geraniol but no cyclic products. The mechanisms of these reactions are discussed.

Purification of riboflavin synthase by affinity chromatography using 7-oxolumazines

Riboflavin synthase (EC. 2.5.1.9) from bakers yeast has been purified over 1000 fold by affinity chromatography using the putative transition-state analogue 6-carboxyethyl-7-oxo-8-D-ribityllumazine as the ligand attached to Sepharose 4B.