Acid catalyzed cyclodimerization of 2,2-bis(trifluoromethyl)-4-alkoxy-oxetanes and -thietanes. Synthesis of 2,2,6,6-tetrakis(trifluoromethyl)-4,8-dialkoxy-1,5-dioxocanes and 3,3,7,7-tetrakis(trifluoromethyl)-9-oxa-2,6-dithia-bicyclo[3.3.1]nonane

• Viacheslav A. Petrov and
• Will Marshall

Beilstein J. Org. Chem. 2010, 6, No. 46, doi:10.3762/bjoc.6.46

• was established by single crystal X-ray diffraction. Keywords: cyclodimerization; electrophilic [4 + 4] cyclodimerization; fluorinated oxetanes; fluorinated thietanes; reaction with alcohols; reaction with H2SO4; Introduction Polyfluorinated 2,2-bis(trifluoromethyl)-4-alkoxy-oxetanes and -thietanes

• temperature. On the other hand, the reaction of 1c with the less acidic (CH3)2CHOH (pKa= 17.1 [15]) was significantly slower taking >10 h for completion at ambient temperature, as monitored by 19F NMR, and led to acetal 3e (Scheme 4). A mechanism for the reaction of these fluorinated oxetanes with Lewis acids