Sequential Peripheral Cyclopropanation as a Synthetic Approach to Cyclosubstituted Triangulanes

The Chemistry of Highly Strained Oligospirocyclopropane Systems

“…A simple methylenation of any bridged methylenetriangulane 164 ( n ≥ 0) will lead to the corresponding cycloannelated triangulane 163 ( n ≥ 0). This multistage strategy has been realized starting from cyclooctene ( 165 ), cyclooctadiene ( 170 ), and cyclooctatetraene ( 173 ) (Scheme ). − The CATs 166 − 169 and 171 and 172 were successfully prepared in overall yields (based on the starting alkene) of 33% ( 166 ), 10% ( 167 ), 16% ( 171 ), and 9% ( 172 ) 62,63b (the yields of several last steps in the preparations of 168 and 169 were not reported 63a ). Hydrocarbons 171 and 172 were obtained as 4:1 mixtures of diastereomers.…”

“…The addition of monohalocarbenes onto methylenecyclopropanes proceeded in low to moderate yields; − ,140b,, therefore, monohalotriangulanes (mainly halospiropentanes) were better prepared by monoreduction of dihalocarbene adducts. 98a,,− 166a Chlorospiropentane itself was obtained by direct chlorination of spiropentane ( 11 ) 166b. Fluoro derivatives of triangulanes are limited to oligofluorospiropentanes which were prepared by cyclopropanation of fluorinated methylenecyclopropanes 167 and allenes 168 or difluorocarbene addition onto methylenecyclopropanes 143,167,169a and allenes .…”

“…Thus,spiropentane (11), according to this definition, is unbranched[2]triangulane ([2]UT), [3]rotane 14 11 is the only possible branched [4]triangulane ([4]BT, other rotanes cannot be called triangulanes), and "davidane" 18 is cyclo [6]triangulane ([6]CT). 59 It has also been proposed to name compounds of type 19 and 20 "cyclosubstituted [n]triangulanes" (CSTs), 59,[62][63][64][65] although the term "cycloannelated[n]triangulanes" (CATs) would be more appropriate. Up to now, several synthetic approaches to UTs and BTs have been successful.…”

The synthesis and characterization of 1′-bromo-1,2-methano[60]fullerene

“…A bromocarbene addition followed by dehydrobromination was outlined to be the key part in the synthesis of the triangulanes. 16 Bromocarbene addition to C 60 was found to go in good to excellent yields with the addition of a strong base such as [(CH 3 ) 3 Si] 2 NNa (NaHMSA) over a mixture of C 60 -CH 2 Br 2 at low temperatures.…”

Reaction of 2,2-dibromotricyclo[7.1.01,9.01,3]decane with methyllithium: synthesis of bicyclo[7.1.0]decadiene-1,2 and dibromotriangulane rearrangement

“…Recently we suggested a synthetic approach to highly energetic branched triangulanes, 1 which consists in the synthesis of corresponding allenes followed by cyclopropanation of the double bonds. 2 We expected that the introduction of an allene fragment into a middle-sized ring will permit us to use these cyclic allenes as starting compounds for the synthesis of peripherally cyclopropanated structures (cyclosubstituted triangulanes 2,3 ). However, only few examples of allenes incorporated into a nine-membered ring are known up to now.…”