Role of the gem-difluoro moiety in the tandem ring-closing metathesis-olefin isomerization: regioselective preparation of unsaturated lactams.
Careful selection of the metathesis catalyst, solvent, and reaction conditions allows for the efficient and regioselective synthesis of isomeric fluorinated and nonfluorinated lactam derivatives II and III from precursor amides I through a ring-closing metathesis (RCM) reaction or a tandem RCM-isomerization protocol, respectively. The presence of the gem-difluoro moiety in the starting materials exerts a pivotal effect by directing the isomerization step, making the overall tandem transformation a regioselective process. The scope, limitations, and synthetic usefulness of this protocol are also discussed.
Fustero
Santos
S
Departamento de Química Organica, Universidad de Valencia, E-46100 Burjassot, Spain. santos.fustero@uv.es
Sanchez-Roselló
María
M
Jiménez
Diego
D
Sanz-Cervera
Juan F
JF
Del Pozo
Carlos
C
Aceña
José Luis
JL