Catalytic Asymmetric Allenylation: Regulation of the Equilibrium between Propargyl- and Allenylstannanes during the Catalytic Process

BINOL: A Versatile Chiral Reagent

“…The same approach proved also to be efficient when applied to propargyltin. Indeed, optically active allenyl alcohols were obtained in that way. , Finally, when 1,4-bis(tri- n -butyltin)but-2-yne or 1-trimethylsilyl-4-tri- n -butyltin-but-2-yne 178 were used, alcohols 179 were prepared in good yields and excellent enantiomeric excesses (Table ). ,− …”

Silylative Carbocyclization of Allenyl-carbonyl Units with Et3SiH Catalyzed by Rhodium: Cis-Stereoselective Synthesis of Homoallylic Cycloalkanols

“…This approach involving the use of rhodium catalyst with trialkylsilane was expanded to silylcarbocyclization of 5-hexyn-1-al to produce ( Z )-exo-triethylsilyl-methylene-1-cyclopentanol as a major product in part of the rhodium-catalyzed silylformylation. , To the best of our knowledge, rhodium- catalyzed silylative carbocyclization of allene derivatives, as well as hydrosilylation of even simple allenes, has not been described. In our continuous efforts to utilize allenyl functionalities, we became quite interested in the development of a novel cyclization of allenyl-carbonyl compound 1 with trialkylsilanes in forming 2 through a rhodium-catalyzed silylcarbocyclization. We recently have disclosed the utility of tethered allenyl-aldehydes and allenyl-ketones as substrates for the transition metal-catalyzed stereoselective carbocyclization to form carbo and heterocycles .…”

Efficient method for propargylation of aldehydes promoted by allenylboron compounds under microwave irradiation

“…The use of less reactive species based on tin [22][23][24], silicon [25] or boron [26][27][28] to perform propargylation reactions typically requires catalysis by Lewis acids or bases and although the utility of allenylstannanes is further indicated by the commercial availability of some of them, the toxicity of these compounds makes them inappropriate for the use in pharmaceutical synthesis [29]. Moreover, the removal of tributyltin residues from reaction mixtures is also a major issue.…”