Studies on the Intramolecular Cycloaddition Reaction of Mesoionics Derived from the Rhodium(II)-Catalyzed Cyclization of Diazoimides
摘要:
A series of alkenyl-substituted imides were prepared by treating the appropriate amide with 2,2,6-trimethyl-4H-1,3-dioxen-4-one in xylene at 140-degrees-C to give the N-acetoacylated imides. Exposure of these imides to standard diazo transfer conditions gave the desired diazoimides. The carbenoid intermediate derived by treatment of the diazoimide with rhodium(II) acetate undergoes ready cyclization onto the neighboring amide carbonyl oxygen atom to generate an isomunchnone intermediate. Subsequent 1,3-dipolar cycloaddition across the pendant olefin affords the cycloadduct in high yield. The stereochemical assignment of several of the cycloadducts was deduced by X-ray crystallography. The stereochemical outcome of the reaction is the consequence of an endo cycloaddition of the neighboring pi-bond across the transient isomunchnone dipole. Molecular mechanics calculations were used to model energy differences between the endo and exo diastereomers. The calculations reveal that the endo diastereomers are significantly (8-12 kcal/mol) lower in energy than the corresponding exo isomers thereby providing a rationale for the preferred endo cycloaddition. Ring opening of the cycloadducts occurred readily producing a transient N-acyliminium ion which either lost a proton to give an enamide or was reduced by Et3SiH to afford a bicyclic piperidine ring.
Studies on the intramolecular cycloaddition reaction of isomünchnones derived from N-alkenyl substituted diazoimides
作者:Albert Padwa、David J. Austin、Alan T. Price、M. David Weingarten
DOI:10.1016/0040-4020(95)01108-0
日期:1996.2
A series of N-alkenylsubstituteddiazoimides were prepared and subjected to Rh(II) catalyzed decomposition. The initially generated rhodium carbenoid undergoes ready cyclization onto the neighboring amide carbonyl oxygen atom to generate an isomünchnone intermediate. Subsequent 1,3-dipolar cycloaddition across the pendant olefin affords the cycloadduct in high yield. The stereochemical assignment
Synthesis of polyheterocyclic ring compounds by the intramolecular cycloaddition of N-alkenyl substituted diazoimides
作者:Albert Padwa、David J. Austin、Alan T. Price
DOI:10.1016/0040-4039(94)85349-5
日期:1994.9
Rhodium(II) catalysis of various diazoimides containing tethered π-systems attached to the nitrogen atom results in isomünchnone dipole formation followed by intramolecular dipolar-cycloaddition.
Amino-bicyclic pyrazinones and pyridinones as coagulation serine protease inhibitors
申请人:Zhang Xiaojun
公开号:US20050038030A1
公开(公告)日:2005-02-17
The present invention relates generally to compounds that inhibit serine proteases. In particular it is directed to novel amino-bicyclic pyrazinone and pyridinone compounds of Formula (I):
or a stereoisomer or pharmaceutically acceptable salt form thereof, which are useful as selective inhibitors of serine protease enzymes of the coagulation cascade; for example thrombin, factor Xa, factor XIa, factor IXa, and/or factor VIIa. In particular, it relates to compounds that are factor VIIa inhibitors. This invention also relates to pharmaceutical compositions comprising these compounds and methods of using the same.
Ethyl 2-diazomalonyl chloride. An efficient diazoacylating reagent
作者:Joseph P. Marino、Martin H. Osterhout、Alan T. Price、Scott M. Sheehan、Albert Padwa
DOI:10.1016/s0040-4039(00)75980-6
日期:1994.1
Ethyl 2-diazomalonyl chloride readily reacts with aromatic and aliphatic amines, alcohols, thiols, and amides for form a variety of alpha-diazo carbonyl species.
AMINO-BICYCLIC PYRAZINONES AND PYRIDINONES AS COAGULATION SERINE PROTEASE INHIBITORS