New routes to conformationally restricted peptide building blocks: a convenient preparation of bicyclic piperazinone derivatives

Intramolecular anodic olefin coupling reactions and the synthesis of cyclic amines

Anodic olefin coupling reactions using a tosylamine trapping group have been studied. The cyclizations are favored by the use of a less-polar radical cation and more basic reaction conditions. The most significant factor for obtaining good yields of cyclic product is the use of the more basic reaction conditions. However, a number of factors including the nature of both the solvent and the electrolyte used can influence the yield of the cyclizations. The cyclizations allow for the rapid synthesis of both substituted proline and pipecolic acid type derivatives.

New synthesis ofcis 5-tert-butyl-L-proline via cuprate. Evaluation as acis proline mimetic in a biological active octapeptide

cis 5-tert-butyl-L-proline (Cbp) was prepared rapidly and efficiently by the addition of low-valent tert-butyl cuprate to an aminal derived from proline. [Cbp(2), D-Leu(5)]-OP was then synthesized, showing a predominant cis peptide bond conformation, as confirmed by NMR.

Conformationally constrained substance P analogues: the total synthesis of a constrained peptidomimetic for the Phe7-Phe8 region

A lactam-based peptidomimetic for the Phe7-Phe8 region of substance P has been synthesized. The synthesis used an anodic amide oxidation to selectively functionalize the C5-position of a 3-phenylproline derivative. The resulting proline derivative was coupled to a Cbz-protected phenylalanine, and an intramolecular reductive amination strategy used to convert the coupled material into a bicyclic piperazinone ring skeleton. The net result was a dipeptide building block that imbedded one of two proposed receptor bound conformations for the Phe7-Phe8 region of substance P into a bicyclic ring skeleton. The building block was then converted into a constrained substance P analogue with the use of solid-phase peptide synthesis. A similar intramolecular reductive amination strategy was used to synthesize a substance P analogue having only Phe7 constrained, and the original 3-phenylproline was converted into a substance P analogue having only Phe8 constrained. All of the analogues were examined for their ability to displace substance P from its NK-1 receptor.

Potent and selective bicyclic lactam inhibitors of thrombin: Part 3: P1' modifications

The synthesis and antithrombotic activity of a series of nonpeptide bicyclic thrombin inhibitors are described. We have explored the SAR around the P1' site. Modification of the P1' site has been found to affect potency and selectivity.

Potent and selective bicyclic lactam inhibitors of thrombin: Part 2: P1 modifications

The synthesis and antithrombotic activity of a series of nonpeptide bicyclic thrombin inhibitors is described. We have explored the SAR with modifications to the P1 site. The introduction of arginine mimetics at the P1 site led to potent and selective thrombin inhibitors.

Potent bicyclic lactam inhibitors of thrombin: Part I: P3 modifications

Peptidomimetic inhibitors of general structure 1 have been prepared. Optimization of the binding affinities of these compounds through variation of the P3 hydrophobic residue is described. Selected substituted bicylic lactams displayed interesting pharmacological profiles both in vitro and in vivo.

Thyrotropin releasing hormone analogs: a building block approach to the construction of tetracyclic peptidomimetics

A building block based approach was used to synthesize a pair of tetracyclic peptidomimetics that constrain all but one of the rotational degrees of freedom of the hypothalamic tripeptide hormone thyroliberin. One of the analogs bound to the thyroliberin endocrine receptor (TRH-R) with an affinity greater than that of an analog without constraints. The tetracyclic peptidomimetics were found to be partial agonists for the TRH-R receptor.

Conformational probes for elucidating the nature of substance P binding to the NK1 receptor: initial efforts to map the Phe7-Phe8 region

Three substance P analogs with conformation constraints in the Phe7-Phe8 region have been prepared in connection with an effort to differentiate two families of potential conformations for the binding of substance P to its NK1 receptor. While the analogs did not bind the NK1 receptor with high affinity, the synthesis of the analogs demonstrated the utility of a general method for constructing piperazinone based peptidomimetics.