SYNTHESES AND STRUCTURAL-PROPERTIES OF DISTELLENES

Citation
R. Gleiter et al., SYNTHESES AND STRUCTURAL-PROPERTIES OF DISTELLENES, Journal of organic chemistry, 63(9), 1998, pp. 2878-2886
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry Inorganic & Nuclear
ISSN journal
0022-3263
Volume
63
Issue
9
Year of publication
1998
Pages
2878 - 2886
Database
ISI
SICI code
0022-3263(1998)63:9<2878:SASOD>2.0.ZU;2-4
Abstract
The syntheses of a mixture of the racemic (a) and the meso form (b) of several derivatives of 2,2'-bi(tricyclo[3.3.0.0(3,7)]octylidene) are described: The 6,6'-diisopropylidene- (4), 6,6'-dimethylidene- (5), 6, 6'-dione- (6), syn-4,4'-dione- (7), anti-4,4'-dione- (8), syn-4-methyl idene-4'-one- (9), anti-4-methylidene-4'-one- (10), syn-4,4'-dimethyli dene- (11), and anti-4,4'-dimethylidene- (12) derivatives. Starting ma terials for all compounds were tricyclo[3.3.0.0(3,7)]octane-2,4-diol ( 19) and its 2,6-isomer 20. Key reaction was the McMurry coupling of 6- isopropylidenetricyclo[3.3.0.0(3,7)]octa (23) or 6-methylidenetricyclo [3.3.0.0(3,7)]octan-2-one (24) to yield 4 or 5, respectively. The McMu rry coupling of the ketone 26 yielded 7 and 8. From the latter, specie s 9-12 could be generated via the Wittig reaction. In most cases only the racemates could be isolated. X-ray investigations on 4a revealed a separation of the isopropylidene groups by 10.3 Angstrom. The central C-C bridging bonds of the stellane units in 4a, 7a, 8a, 12a, and 30 C (1)-C(5), C(3)-C(7), C(1)-C(5'), C(3')-C(7') were found to be between 1.596(2) and 1.616(3) Angstrom. In 4a we found a twisting between the terminal isopropylidene groups by a torsion ((CH3)(2)C=C ... C=C(CH3)( 2)) of 74 degrees and 83 degrees, respectively, in both independent mo lecules. The twist angle between the CO groups in 7a amounts to 53 deg rees, and in 8a to 118 degrees. The same twist angle was found between the exo-methylidene groups in 12a.