The efficient synthesis of dibenzo[d,d′]benzo[1,2-b:4,3-b′]dithiophene and cyclopenta[1,2-b:4,3-b′]bis(benzo[d]thiophen)-6-one

• Zhihua Wang,
• Sheng Zhu,
• Jianwu Shi and
• Hua Wang

Beilstein J. Org. Chem. 2009, 5, No. 55, doi:10.3762/bjoc.5.55

• ] as starting material, dibenzo[d,d′]benzo[1,2-b:4,3-b′]dithiophene, a [5]heterohelicene, was synthesized efficiently in 60% yield via formylation and McMurry reaction. Cyclopenta[1,2-b:4,3-b′]bis(benzo[d]thiophen)-6-one, another interesting helical ketone, was also prepared in 79% yield via

• deprotonation and ketonization of 3,3′-bi[benzo[b]thiophenyl]. In addition, the single-crystal structure of dibenzo[d,d′]benzo[1,2-b:4,3-b′]dithiophene and UV–vis spectra of both title compounds are described. Keywords: crystal structure; cyclopenta[1,2-b:4,3-b′]bis(benzo[d]thiophen)-6-one; dibenzo[d,d′]benzo

• reaction and its crystal structure was determined. In addition, cyclopenta[1,2-b:4,3-b′]bis(benzo[d]thiophen)-6-one (2), an interesting helical ketone, was also prepared via deprotonation and ketonization of 3. Results and Discussion Synthesis Scheme 1 shows the synthetic route to 1 and 2. With 3 as