Tellurium-mediated cycloaromatization of acyclic enediynes under mild conditions.

The cycloaromatization of acyclic enediynes typically requires very high temperatures (>160 °C) and dilute conditions to proceed in a synthetically useful yield. These conditions hinder reaction throughput, inhibiting the use of this reaction for the large-scale production of materials. The reaction of sodium telluride with acyclic arenediynes yields the corresponding tellurepine, which under gentle heating extrudes Te° to yield the cycloaromatization product. We have developed conditions that form sodium telluride from inexpensive tellurium metal in situ, and that also perform the desilylation of silylated arenediynes in the same process. Under our conditions, we are able to perform desilylation and cycloaromatization at temperatures as low as 40 °C and on a scale as large as 5 g in standard laboratory glassware.