Inderjit S. Mann

A versatile synthesis of fully aromatic benzo[c]phenanthridine alkaloids

Abstract A versatile new approach for the synthesis of benzo[ c ]phenanthridine alkaloids is described and is illustrated by the preparation of eight different alkaloids. The key steps are Smiles rearrangements, which allow easy access to 2-bromo-1-naphthylamines from 2-bromo-1-naphthols, and the attachment of the D-ring unit by Suzuki coupling.

Dynamic kinetic resolution-asymmetric transfer hydrogenation of 1-aryl-substituted cyclic ketones

Abstract A range of 1-aryl-2-tetranols, and 1-phenyl-2-indanol, have been generated in high yield and enantiomeric excess from the corresponding racemic ketones, via a dynamic kinetic resolution–transfer hydrogenation process, using Ru(II)-TsDPEN in formic acid/triethylamine (5:2). This provides a potential entry to an asymmetric total synthesis of benzazepines such as Sch 39166.

The effect of catalyst loading and donor ligands in the Mn(III) salen catalysed chiral epoxidation of chromenes: Synthesis of BRL 55834

Abstract In the absence of a donor ligand both the reaction rate and product e.e. of the manganese (III) salen catalysed epoxidation of 2,2-dimethyl-6-pentafluoroethylchromene were dependent on the catalyst loading. Isoquinoline N-oxide was the most effective donor ligand, affording highly efficient epoxidations with catalyst loadings of 0.1–0.4 mol%. These findings allowed the realisation of a concise, inexpensive synthesis of BRL 55834.

A Direct and High Yielding Route to 2-(5-Tetrazolyl) Substituted Benzopyran-4-ones: Synthesis of Pranlukast

Abstract A direct and high yielding route to 2-(5-tetrazolyl)benzopyran-4-ones 1, including pranlukast 1a is described. This involves the Claisen condensation reaction between the relevant hydroxyacetophenone 2 and the ethyl ester of tetrazole-2-carboxylic acid 5 to give the 1,3-diketone 6, which is then cyclised to give the desired benzopyran-4-ones 1.

Stereoselectivity in the Peterson reaction - application to the synthesis of BRL 49467.

Abstract The E:Z selectivity in the introduction of the tri-substituted double bond in BRL 49467 could be controlled by the choice of base and silyl group used in a Peterson olefination reaction. The method allowing optimum E-selectivity was developed such that it could be scaled up to 100mmol.

A versatile synthesis of benzo[c]phenanthridine alkaloids

Suzuki coupling between 2-bromo-1-formamidonaphthalenes and arylboronic acids is the key step in a versatile synthesis of benzo[c]phenanthridine alkaloids, illustrated by the synthesis of norallonitidine, nornitidine, noravicine, allonitidine, nitidine and avicine.