Constrained peptidomimetics: building bicyclic analogs of pyrazoline derivatives

Construction of pyrazolodiazepines using AuI, a dual functional gold catalyst

N,N'-5,7-Fused compounds are important molecules exhibiting medicinal potential. Herein, we report a practical and robust method for synthesising pyrazolodiazepines from N-piperidinyl alkynylhydrazides using a AuI catalyst. The broad substrate scope of alkynylhydrazides and synthetic application of pyrazolodiazepines are demonstrated. In addition, control experiments provide detailed information on the reaction mechanism, in which AuI promotes both the sequential intramolecular nucleophilic addition and the double nucleophilic substitution reaction as a π-acidic and nucleophilic dual functional catalyst.

Mechanisms of phosphine-catalyzed [3+3] cycloaddition of ynones and azomethine imines: a DFT study

Mechanisms of PPh₃-catalyzed [3+3] cycloaddition between a ynone and an azomethine imine.

Ir/PTC cooperatively catalyzed asymmetric umpolung allylation of α-imino ester enabled synthesis of α-quaternary amino acid derivatives bearing two vicinal stereocenters

A novel Ir/PTC (phase-transfer catalyst) cooperatively catalyzed asymmetric umpolung allylation of simple α-imino esters is developed and it provides facile access to α-quaternary amino acid derivatives bearing two vicinal stereocenters. Both the metal catalyst and the phase-transfer catalyst are crucial for this methodology. The reaction features good yields, high diastereo- and enantio-selectivities, ease of scale-up to gram scale and further transformation of the products (e.g. to quaternary proline analogues with multi stereocenters).

Intramolecular hydroamination of dithioketene acetals: an easy route to cyclic amino acid derivatives

Catalytic intramolecular hydroamination of dithioketene acetals was developed for the synthesis of cyclic amino acid derivatives. Triggered by the addition of a catalytical amount of n-BuLi, the reaction proceeds to give proline and pipecolic acid derivatives in excellent yields and diastereoselectivity.

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.

Orally active thrombin inhibitors. Part 2: Optimization of the P2-moiety

Synthesis and SAR of orally active thrombin inhibitors of the d-Phe-Pro-Arg type with focus on the P2-moiety are described. The unexpected increase in in vitro potency, oral bioavailability, and in vivo activity of inhibitors with dehydroproline as P2-isostere is discussed. Over a period of 24h the antithrombin activity of the most active inhibitors with IC(50)s in the nanomolar range was determined in dogs demonstrating high thrombin inhibitory activity in plasma and an appropriate duration of action after oral administration.