title: Catalytic oxidative carbonylation of primary and secondary diamines to cyclic ureas. Optimization and substituent studies.
abstract: W(CO)(6)-catalyzed oxidative carbonylation of 1,3-propanediamine to the corresponding urea has been examined under a variety of conditions. Following optimization, the Thorpe-Ingold effect on ring closure was studied using 2,2-dialkyl-1,3-propanediamines. For the 2,2-dimethyl- and 2,2-dibutyl-1,3-propanediamines, the yields were increased significantly as compared to that of the unsubstituted case. The eight-membered cyclic urea 5-butyl-5-ethyl-1,3-diazepan-2-one (5f) was formed in 38% yield, while only trace amounts of the cyclic urea were produced from the parent 1,5-pentanediamine. In a study of secondary diamines, yields from the carbonylation of N,N'-dialkyl-2,2-dimethyl-1,3-propanediamines were lower than those obtained from the primary diamines. The main byproducts from secondary diamines were tetrahydropyrimidine derivatives formed from a competitive reaction of the substrate with the oxidant and base.
authors.affiliation: Department of Chemistry and Center for Catalysis, University of Florida, Gainesville 32611-7200, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Qian
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: McCusker
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.forename: A Denise
authors.initials: AD
authors.lastname: Main
authors.forename: Mary
authors.initials: M
authors.lastname: Chlebowski
authors.forename: Michiyo
authors.initials: M
authors.lastname: Kokka
authors.forename: Lisa
authors.initials: L
authors.lastname: McElwee-White