Abstract: Pentalenene, the neutral precursor to pentalenic acid and a variety of pentalenolactones, has been synthesized from 4, 4-dimethyl-2-cyclopentenone. Following hydrosilation, dichloroketene addition, and hydrolysis, ring expansion to the highly functionalized bicyclo [3.3. 0] octanone 22 was achieved with diazomethane. Reduction with zinc and acetic acid led to regiospecific a-chloro enone formation. In six additional steps, ...
![6,6-dichloro-5-hydroxy-3,3-dimethylbicyclo[3.2.0]heptan-7-one Structure](https://image.chemsrc.com/caspic/233/82352-49-6.png)
![7,7-dichloro-3,3-dimethyl-1-(triethylsiloxy)bicyclo[3.2.0]heptan-6-one Structure](https://image.chemsrc.com/caspic/309/82352-47-4.png)