Christopher J. May

Iodocyclisations of allyl- amidines and-ureas

Abstract Iodocyclisation of allyl-amidines (1) and-ureas (4) gives imidazolines (2) and imidazolinones (5) respectively; in contrast, bromocyclisation of the amidine (1a) results in formation of the six-membered ring (3).

A convenient precursor to 3,4-didehydropyridine

Abstract The preparation of 3-(3,3-dimethyltriazen-l-yl)pyridine-4-carboxylic acid ( 5 ), a convenient shelf-stable precursor to 3,4-didehydropyridine, is described.

A new precursor to 3,4-didehydropyridine, and its use in the synthesis of the antitumour alkaloid ellipticine

A concise synthesis of the antitumour alkaloid ellipticine (1) is reported. The route involves a Diels-Alder reaction between 1,4-dimethylpyrano[3,4-b] indol-3-one (3), easily prepared in two steps from indole, and 3,4-didehydropyridine (4), and for its successful execution required the development of a new thermal, reagent-free precursor to the aryne. This precursor, 3-(3,3-dimethyltriazen-1-yl)pyridine-4-carboxylic acid (10a), prepared from 3-aminopyridine-4-carboxylic acid, decomposes in boiling acetonitrile to generate 3,4-didehydropyridine which can be intercepted in Diels-Alder reactions with tetraphenylcyclopentadienone, furan, and 2,5-dimethylfuran. The triazenes (10b) and (10c) can be prepared and decomposed similarly. The key Diels-Alder reaction between the pyranoindolone (3) and 3,4-didehydropyridine (4) gives ellipticine (1) in 20% yield, together with an equal amount of isoellipticine (14).

A concise synthesis of the antitumour alkaloid ellipticine

A short synthesis of the antitumour alkaloid ellipticine, based on the Diels–Alder reaction between 1,4-dimethylpyrano[3,4-b]indol-3-one (2) and 3,4-didehydropyridine, is described.

Ring opening and insertion reactions of endo-alkoxy-tetraphenylcyclobutenylpalladium(II) derivatives

endo-Alkoxy-tetraphenylcyclobutenylpalladium-(II)β-diketonates readily undergo a stereospecific ring opening to give 4-alkoxytetraphenylbuta-1-cis, 3-trans-dienylpalladium complexes which undergo insertion reactions with unsaturated hydrocarbon substrates.