40651-95-4

An efficient and practical synthetic protocol for the synthesis of 1,4-disubstituted pyrrolo[1,2- a ]pyrazine derivatives is described that originates from α-substituted pyrroloacetonitriles which, in turn, are readily available from aryl and alkyl aldehydes. The α-pyrroloacetonitriles were subjected to a Friedel-Crafts acylation with methyl chlorooxoacetate followed by reduction of the nitrile group under Pd-catalyzed hydrogenation conditions and finally aromatization with DDQ leading to the desired pyrrolo[1,2- a ]pyrazine derivatives. This method was generalized and successfully applied to various aryl, heteroaryl, and alkyl substrates. The developed protocol provides direct and convenient access to 1,4-disubstituted ring systems in moderate to good overall yields (51-68percent) without the need for purification of the intermediates. Further functionalization via the stepwise halogenation (bromination, iodination) and nitration was also demonstrated. In addition, the potential of the ester functionality for elaboration was demonstrated by manipulating into heterocyclic ring systems, exemplified by conversion into benzoxazole derivatives.

α-Aminonitrile was an important building block in natural products and key intermedia in organic chemistry. Herein, the direct amination of cyanohydrins with the partner of ammonia to synthesis N-unprotected α-aminonitriles is developed. The reaction proceeds via titanium-catalyzed cyano-borrowing reaction, which features high atom economy and simple operation. A broad range of ketone or aldehyde cyanohydrins was tolerated with ammonia, and the N-unprotected α-aminonitriles were synthesis with moderate to high yields under mild reaction conditions.

Their ready availability from simple starting materials in only two synthetic steps and their versatility as building blocks for the construction of highly substituted amines and N-heterocycles renders α-(alkylideneamino) nitriles useful synthetic intermediates. Herein, short syntheses of tri- and tetrasubstituted pyrroles including the northern half of the HMG-CoA reductase inhibitor atorvastatin as well as an access to 3-substituted indolizidines will be described. Georg Thieme Verlag Stuttgart - New York.

A series of disubstituted ureas containing amide or amine groups was prepared and evaluated for their ability to inhibit acyl-CoA:cholesterol O- acyl transferase in vitro and to lower plasma total cholesterol in a variety of cholesterol-fed rat models in vivo. The presence of polar or ionizable functionalities within this class of compounds may impart greater aqueous solubility to those compounds and thus allow improved transport to the enzyme location within the intestinal enterocyte. Compounds from this class exhibit good cholesterol lowering in a chronic cholesterol-fed rat model of hypercholesterolemia even when dosed in an aqueous vehicle. In general, the amine-containing compounds were more potent and efficacious than the amides in the acute rat model of hypercholesterolemia. Further structure-activity relationship studies showed that the preferred position of the amide/amine group was β to the urea moiety and not α, and that in this series, the presence of a secondary amine (or amide) proton is required for good in vitro potency. One of these compounds, 9n(-), lowered plasma total cholesterol (- 47%) and elevated high-density lipoprotein cholesterol (+256%) when dosed in an aqueous vehicle to rats with preestablished hypercholesterolemia.