合成路线1

The addition of 2-(trimethylsilyl)ethylmercaptane (I) to 2,4-hexadiyn-1,6-diol (II) catalyzed by KOH in DMF gives the addition product (III), which is oxidized with Dess-Martin periodinane in dichloromethane or oxalyl chloride in DMSO yielding the dialdehyde (IV). The condensation of (IV) with tetrabromomethane by means of triphenylphosphine in dichloromethane affords the tetrabromo derivative (V), which is treated with butyllithium in THF to give the diacetylenic dianion (VI). The reaction of (V) with methyl iodide yields the methylated monoanion (VII), which is condensed with DMF catalyzed by boron trifluoride ethearate to afford the diacetylenic aldehyde (VIII). The reaction of (VIII) with tetrabromomethane/triphenylphosphine as before gives the dibromovinyl derivative (IX), which is treated with butyllithium as before yielding the triacetylenic compound (X). The condensation of (X) with vinyl bromide (XI) by means of Pd(PPh3)4/CuI/triethylamine in toluene affords the intermediate (XII), which is finally submitted to an oxidative cyclization by means of tetrabutylammonium fluoride and iodine.