Towards the synthesis of insulated oligoynes: A ring-closing-metathesis approach to molecular encapsulation

Masked hexayne 18 was prepared in 11 steps from commercially available reagents. The four butenyl substituents contained within the two arylsilane residues in 18 have been used in a double ring-closing-metathesis operation in an attempt to encapsulate the π-conjugated framework. When 18 was treated with Grubbs’ 1st generation metathesis catalyst however, double ring-closing metathesis provided macrocycle 19 as the major product in good yield. Reasons why the macrocycle in 19 crowns, rather than encapsulates, the π-conjugated framework are discussed.

Masked hexayne 18 was prepared in 11 steps from commercially available reagents. Attempted molecular encapsulation of the π-conjugated framework using a double ring-closing-metathesis operation generated 19, where the desired macrocycle crowns, rather than encapsulates, the unsaturated framework.Figure optionsDownload as PowerPoint slide