The mass spectral fragmentation of isoxazolyldihydropyridines

The mass spectral fragmentation of 4-isoxazolyl-1,4-dihydropyridines has been examined with the aid of linked metastable scanning. Three prominent pathways involve (i) O-N bond cleavage of the isoxazole followed by the loss of R2CN, (ii) loss of carboalkoxy from the 3- and/or 5- position of the dihydropyridine and, (iii) loss of the 4-isoxazolyl-substituent.

[1]  N. R. Natale,et al.  The reaction of lithio-alkyl-isoxazoles with acid chlorides in the presence of cerium trichloride. Direct preparation of β-keto-isoxazolyl compounds , 1986 .

[2]  C. Niou,et al.  Synthesis, metalation and electrophilic quenching of alkyl-isoxazole-4-tertiary carboxamides: a critical comparison of three isoxazole lateral metalation methods , 1986 .

[3]  H. Hope,et al.  Metalation of isoxazolyloxazolines, a facile route to functionally complex isoxazoles: utility, scope, and comparison to dianion methodology , 1985 .

[4]  C. Niou,et al.  A facile synthesis of functionally complex isoxazole derivatives , 1985 .

[5]  N. Filipović-Marinić,et al.  Mass spectra of some tetrasubstituted 4,4′‐biisoxazoles and 4,4′‐methylendiisoxazoles , 1984 .

[6]  D. Quincy,et al.  Neutral Dichromate Oxidation. Preparation and Utility of Isoxazole Aldehydes , 1983 .

[7]  F. Bossert,et al.  4‐Aryldihydropyridines, a New Class of Highly Active Calcium Antagonists , 1981 .

[8]  W. Haddon.  The constant neutral linked magnetic field electric sector scan , 1980 .

[9]  W. Haddon.  Computerized mass spectrometer linked scan system for recording metastable ions , 1979 .

[10]  A. Mancuso,et al.  Oxidation of long-chain and related alcohols to carbonyls by dimethyl sulfoxide "activated" by oxalyl chloride , 1978 .

[11]  E. Esmans,et al.  Mass Spectra of Substituted 4-Cyano-1,4-dihydropyridines , 1978 .

[12]  E. Esmans,et al.  The N.M.R. and Mass Spectroscopic Studies of 3-Acetyl-5-alkyl-1-benzyl-1,4-dihydropyridines , 1977 .

[13]  R. Dommisse,et al.  Mass spectra of 4‐substituted‐1,2,6‐trimethyl‐3,5‐diethoxycarbonyl‐1,4‐dihydropyridines , 1975 .

[14]  T. Nishiwaki.  Mass spectrometry of isoxazole derivatives—III: Skeletal rearrangement ions in the mass spectra of isoxazoles having a heteroatom at C5 , 1971 .

[15]  D. C. Nonhebel.  The mass spectra of some 3,5‐diarylisoxazoles , 1970 .

[16]  M. Ohashi,et al.  Mass spectra of some alkyl isoxazoles , 1969 .

[17]  T. Nishiwaki.  Mass spectrometry of 5-alkoxyisoxazoles and isoxazol-5-ones , 1969 .

[18]  R. Cooks,et al.  Electron impact studies. XXXVII. Skeletal-rearrangement fragments in the mass spectra of alkyl and aryl isoxazoles , 1969 .

[19]  H. Nakata,et al.  The primary fragmentation step of isoxazole upon electron impact. A correlation with photochemistry , 1968 .

[20]  Dudley H. Williams,et al.  The mass spectra of some alkyl and aryl oxazoles , 1968 .

[21]  M. Ohashi,et al.  The lability of nitrogen-oxygen linkage of isoxazoles upon electron impact , 1968 .