Neighboring Group Participation in a Regio- and Stereoselective Chlorination of a Bicyclo[2.2.2]octanone

Abstract

The zinc chloride-mediated acetylation of the optically active silyl enol ether 2a gave the beta-diketone 3a (48%) together with the regio- and stereoselectively chlorinated compound 4 (27%). The yield of 4 increased to 70% by starting from the O-acetyl derivative 2c. The chlorination most likely occurs via neighboring group participation by the endo acetoxy group.

Spirobicyclo[2.2.2]octane derivatives: mimetics of baccatin III and paclitaxel (Taxol)

“…The exo : endo ratio in the best case was 80 : 20, which was not improved by the use of the corresponding TBDMS-protected derivative. 41 In addition to the C-alkylation products substantial amounts of two O-alkylation products were formed in all cases, despite the use of several methods that were recommended to avoid reactions at oxygen. [42][43][44][45][46] Hydrolysis of the two O-alkylation products regenerated 12 but only product 13a was used for further synthesis.…”

“…A solution of 12 41 (554 mg, 2.47 mmol) in toluene (6 mL) was added to Cs 2 CO 3 (1.14 g, 3.50 mmol) in toluene (6 mL) at room temperature. 2-(2-Iodoethyl)-1,3-dioxolane (1.20 g, 6.14 mmol, 2.5 equiv.)…”

Screening of yeast species for the stereo-selective reduction of bicyclo[2.2.2]octane-2,6-dione

“…Optically active bicyclo[2.2.2]octane derivatives have been used as rigid templates for regio-and stereo-controlled transformations towards natural products. 1,2 Several other applications for bicyclo[2.2.2]octane derivative in organic synthesis have been reported, 3 such as building blocks for mono-and sesquiterpenoids, 4,5 isopropyl hemiesters 6 and as synthons for taxanes. 7 Biotransformations are generally regarded as an efficient means to produce non-racemic building blocks.…”