Carbon–carbon cross-coupling reactions are very important in the areas of material science and medicinal chemistry. Most current methods require expensive transition-metal catalysts (for example, based on Cu, Pd, Co, Ni, Pt, Ru, and Rh) and ligands (for example, phosphines). Early reports by Kharasch and Reinmuth in 1954 and then by Tamura and Kochi in 1971 suggested that inexpensive Grignard r...

The 5'-alkynylation of uridine-derived aldehydes is described. The addition of alkynyl Grignard reagents on the carbonyl group is significantly influenced by the 2',3'-di-O-protecting groups (R1): O-alkyl groups led to modest diastereoselectivities (65:35) in favor of the 5'R-isomer, whereas O-silyl groups promoted higher diastereoselectivities (up to 99:1) in favor of the 5'S-isomer. A study r...

The development of cascade reactions—often called domino, tandem, or multicomponent reactions—is a major challenge in chemistry because of the difficulties in carrying out multiple reactions in one vessel. These reactions are attractive goals because they save time and materials while producing less waste than the tradition method of carrying out reactions one at a time followed by purification...

Methynolide and 10-epi-methynolide were synthesized from the necessary segments, which were prepared by the addition of Grignard reagents to the corresponding alpha-alkoxyketones utilizing 1,2-stereochemical selection based on Cram chelation control. Ring-closing metathesis, as the key reaction, was carried out to combine the segments for the synthesis of methynolide and 10-epi-methynolide. The...

A practical and highly stereoselective approach to access 2,6-disubstituted piperidines using an amidine auxiliary is reported. Following the diastereoselective addition of Grignard reagents at the 2-position of an activated pyridinium salt, the amidine group directs a regioselective metalation at the 6-position, enabling further functionalization. A subsequent electrophilic quench or a Negishi...