title: 1,3-dipolar cycloadditions of trimethylsilyldiazomethane revisited: steric demand of the dipolarophile and the influence on product distribution.
abstract: The 1,3-dipolar cycloaddition of trimethylsilyldiazomethane with alpha,beta-unsaturated esters was examined. The resulting 1-pyrazolines isomerize to regioisomeric 2-pyrazolines (a or b) or undergo desilylation (c). Acrylates yield only b or c. beta-Substituted dipolarophiles may yield all three types of products. This work demonstrates that the distribution of 2-pyrazoline products is highly dependent on the relative configuration of the substituents on the 1-pyrazoline intermediate.
authors.affiliation: Department of Chemistry, Florida International University, Miami, Florida 33199, USA.
authors.forename: Dragan
authors.initials: D
authors.lastname: Simovic
authors.forename: Mingping
authors.initials: M
authors.lastname: Di
authors.forename: Vered
authors.initials: V
authors.lastname: Marks
authors.forename: David C
authors.initials: DC
authors.lastname: Chatfield
authors.forename: Kathleen S
authors.initials: KS
authors.lastname: Rein
mesh_terms: D003500:Cyclization; D003978:Diazomethane / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D004952:Esters / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism; D014297:Trimethylsilyl Compounds / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D004952:Esters; D014297:Trimethylsilyl Compounds; D003978:Diazomethane; C060070:trimethylsilyldiazomethane