194019-64-2Relevant academic research and scientific papers
Asymmetric synthesis of 3,4-disubstituted pyrrolidines: 1,3-dipolar addition to chiral bicyclic lactams
Meyers, Albert I.,Fray, Andrew H.
, p. 283 - 298 (2007/10/03)
The title compounds 1 are obtained in good yields from tricyclic lactams 2, which are derived from the asymmetric dipolar cycloaddition of azomethine ylides 4 to chiral bicyclic lactams 3.Thus, treatment of tricyclic adducts 14 or 17 with methyllithium gives N-substituted bicyclic hydroxylactams 16 or 18, respectively, as a consequence of abstraction of the kinetically acidic benzylic hydrogen followed by an anionic cycloreversion process.Alternatively, treatment of 14 or 48 with calcium metal in liquid ammonia gives N-unsubstituted bicyclic hydroxylactams 60 or 56 respectively.Through the intermediacy of these bicyclic hydroxylactams, illustrative examples of nonracemic monocyclic and bicyclic 3,4-disubstituted pyrrolidine 'building blocks' were synthesized bearing vicinal substituents which are amenable to facile chemical manipulation. - Keywords: 3,4-disubstituted pyrrolidine; asymmetric synthesis; 1,3-dipolar addition; bicyclic lactam; hydroxylactam
