title: One pot synthesis of maleimide and hydantoin by Fe(CO)5 catalyzed [2 + 2 + 1] co-cyclization of acetylene, isocyanate and CO.
abstract: In the presence of a catalytic amount of Fe(CO)(5), terminal acetylenes, isocyanates and CO undergo [2 + 2 + 1] cyclization to form substituted maleimides and hydantoins; when internal alkynes are used, exclusive maleimide formation is observed. While the maleimides can be obtained as the major products, in up to 90% yield, when the reaction is carried out in CO atmosphere, in absence of CO, the hydantoins are formed in up to 87% yield. Formation of maleimides has been shown to occur via the formation of a ferrole intermediate, whereas the hydantoins are proposed to form through successive insertion of isocyanate into the iron-acetylide bond. All compounds were characterized by spectroscopic methods and molecular structures of some compounds were established by single crystal X-ray diffraction method.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India. mathur@iitb.ac.in
authors.forename: Pradeep
authors.initials: P
authors.lastname: Mathur
authors.forename: Raj Kumar
authors.initials: RK
authors.lastname: Joshi
authors.forename: Dhirendra Kumar
authors.initials: DK
authors.lastname: Rai
authors.forename: Badrinath
authors.initials: B
authors.lastname: Jha
authors.forename: Shaikh M
authors.initials: SM
authors.lastname: Mobin