ABSTRACT
An rapid and mild synthetic route for the preparation of cyclic tetrasubstituted platforms via ruthenium-catalyzed ring-closing metathesis (RCM) has been developed. This process tolerates a wide range of functionalities such as nitrogen, oxygen, sulfur, silicon, and carbon tethered groups, as well as very challenging fluorine and boron atoms (36 derivatives, up to 96%). This diversity-oriented method was further demonstrated by the postfunctionalization reactions, such as Pd-couplings, N-substitution, and reductive amination introducing a morpholine moiety.
ABSTRACT
Cyclization of silylenolether-ynesulfonamides proceeds at ambient temperature under mild reaction conditions under silver catalysis. Bridged compounds were obtained exclusively through 7-exo-dig reactions. The protocol is applicable to a wide range of substrates, thus leading to azabicyclic frameworks.
ABSTRACT
Sequential deprotonation, isomerization of 3-alkynoates and subsequent 1,2-addition led to bicyclic allenoate in the presence of a catalytic amount of Cs2CO3. Cyclization proceeds in a totally stereoselective manner in the case of the two-carbon linker chain. A one-pot reaction starting from alkynyl ketones afforded tricyclic fused ring systems with good yields.