Ian Patel

The direct synthesis of novel enantiomerically pure α-amino acids in protected form via Suzuki cross-coupling

Abstract Protected allylglycine has been hydroborated and the intermediate organoborane employed in Suzuki coupling reactions with a number of olefinic, aromatic and heteroaromatic bromides and iodides to produce a range of novel α-amino acids in good, unoptimised yields.

A concise, stereoselective synthesis of meso-2,6-diaminopimelic acid (DAP)

The preparation of meso-2,6-diaminopimelic acid 1 is described. The key step in the synthesis is Suzuki coupling of the novel organoboron homoalanine equivalent 3 with methyl (2Z)-3-bromo-2-[(tert-butoxycarbonyl)amino]-2-propenoate 5.

An asymmetric synthesis of a 4-substituted-1,4-dihydropyridine

Abstract A concise, convergent asymmetric synthesis of the 4-substituted-1,4-dihydropyridine 1 [Ohnmacht, C. J., Jr.; Trainor, D. A.; Forst, J. M.; Stein, M. M.; Harris, R. J. Patent No. 5,622, 964] has been achieved via a novel asymmetric Michael addition of an optically pure vinylogous amide to an α,β-unsaturated ketone. The overall process is three steps from readily available starting materials and provides an economical manufacturing route to the title compound, which was required as a candidate drug for the treatment of urinary incontinence.

Hydroboration–Suzuki cross coupling of unsaturated amino acids; the synthesis of pyrimine derivatives

Abstract Hydroboration of protected allylglycines with 9-BBN followed by Suzuki cross coupling of the resulting organoboranes proceeded smoothly giving a range of new bis-homophenylalanine and related derivatives in good yields (9 examples, 53–64%). One of the Suzuki coupling products has been elaborated to give the N-Cbz-protected natural product pyrimine. The hydroboration–Suzuki coupling of vinylglycine derivatives was also studied but was less efficient than with the allylglycine derivatives: the best results were obtained using disiamylborane·DMS as the hydroborating agent.

Heck reactions of amino acid building blocks: application to the synthesis of pyrrololine analogues

Heck reactions of unsaturated amino acid building blocks are described which allow access to homo- and bis-homophenylalanine derivatives and to γ,δ-unsaturated amino acids. Preliminary synthetic studies utilising this chemistry for the preparation of pyrrololine and deoxypyrrololine analogues are also reported.