Two distinct mechanisms of alkyne insertion into the metal-sulfur bond: combined experimental and theoretical study and application in catalysis.

The present study reports the evidence for the multiple carbon-carbon bond insertion into the metal-heteroatom bond via a five-coordinate metal complex. Detailed analysis of the model catalytic reaction of the carbon-sulfur (C-S) bond formation unveiled the mechanism of metal-mediated alkyne insertion: a new pathway of C-S bond formation without preliminary ligand dissociation was revealed based on experimental and theoretical investigations. According to this pathway alkyne insertion into the metal-sulfur bond led to the formation of intermediate metal complex capable of direct C-S reductive elimination.

Remarkable ligand effect in Ni- and Pd-catalyzed bisthiolation and bisselenation of terminal alkynes: solving the problem of stereoselective dialkyldichalcogenide addition to the C triple chemical bond C Bond.

We have developed two new catalytic systems based on Ni and Pd complexes to solve the challenging problem of dialkyldichalcogenide (Alk2E2; E=S, Se) addition to alkynes. A comparative study of two catalytic systems-Ni/PMe2Ph and Pd/PCy2Ph-has revealed that the Ni catalyst is superior with respect to high catalytic activity and more general scope relative to the Pd system. A novel synthetic methodology was developed for the preparation of (Z)-bis(alkylthio)alkenes and (Z)-bis(alkylseleno)alkenes from terminal alkynes with excellent stereoselectivity and high yields.