A convenient method for the two-step synthesis of arenediynes from 1,2-arenedialdehydes is reported. Dibromomethylenation of dialdehydes under Corey-Fuchs conditions (CBr4, Ph3P, Zn) provides the tetrabromides in excellent yields. Treatment of the tetrabromides with n-BuLi or LDA affords 3,4-unsaturated 1,5-diynes, the key structural moiety present in several naturally occurring antitumour antibiotics, in varying yields. The key intermediates in these transformations appear to be vinylidenecarbenes or carbenoids, generated in situ via metal-halogen exchange and elimination.
Bibliographical noteFunding Information:
The authors thank DST, India, for financial assistance and SAIF, IIT Bombay, for NMR data. B.S. thanks CSIR, India, for a scholarship.
- Fritsch-Buttenberg-Wiechell rearrangement