Pentacyclo dodecan

With palladium(O) in the presence of phosphane ligands, the selectivity of the reaction is much lower. Besides 67% polymeric material, a 33% combined yield of cycloaddition products is obtained with a palladium/triphenylphosphane molar ratio of 1 1 after 2 hours at room temperature with complete conversion. The cycloaddition products consist of the dimer 30 (12%), methyl 3,3,7,7-tetramethoxy-exo-tricyclo[4.1.0.0 ]heptane-5-acetate (32, 71%) as the decomposition product of the primarily formed 5-(2,2-dimethoxyethenyl)-3,3,7,7-tetramethoxy-e.V( -tricyclo[4.1.0.0 ]heptane (31), and 3,3,6,6,9,9,12,12-octamethoxy-exo,enrfo,cxo-pentacyclo [9.1.0.0 . 0 . 0 i°]dodecane (33, 17%). 

Stdn. Belichlung ivie oben COOC2h5 H5C2OOcYzjfcOOC2H5 C00C2Hs 1,5,7,11-Tetranthoxy-carbonyl-3,9-diaza-pentacyclo [6.4.0. OV.fhMhO5.10] dodecan 35 160-161 4... 

Die Reduktion von 3,6-Dioxo-pentacyclo[6.2.2.02 7.04 ,0.05 9]dodecan liefert in Zink/Eisessig ein Hemiacetal5, wahrend in starker acidem Medium Spaitung und Neu-knupfung von C—C-Bindungen beobachtet wird (s.S. 734). 

Dieldrin in concentrated solution or in the solid state is converted by the action of light to photo-dieldrin (54) of the structure 4,5-eJco-epoxy-l,9,10,10,ll-ejco-12-hexachloro-8,3,7,6-enacute toxicity to warm-blooded organisms is also higher than that of dieldrin. 

Photoreactions of Thymines etc. - The uracil derivative (184) undergoes photochemical transformation when it is irradiated in frozen benzene with added trifluoroacetic acid. Cyclodimerization occurs yielding derivatives of diaza-pentacyclo[6.4.0.0 . 0 . 0 ]dodecane derivatives such as (185). Other addition products (186) and (187) were also identified. The photoreduction of 5-bromo-uracil (188) has been studied. ... 

These results substantiate the mechanism that pentacydic compounds (12x) are derived from the tautomeric isomer (7x) by way of the semibuUvalene intermediate (15x) followed by rearrangement to pentalenopyrimidine (16x). Thus, the present work demonstrates that pentacyclo[6.4.0.0. > 0. 0 ]dodecanes (3x)... 

As described above, each pentacyclo[6.4.0.0 >. 0 > 0 > ]dodecane (2a-d) includes a methylene group at C6 or C7 as a component, suggesting that the presence of a methylene group at C6 or C7 in the precursory cyclobutaquinazoHne maybe important for the construction of the ring system (Scheme 19). ... 

In contrast, UV irradiation of llfi, which retains the double bond between C5 and C6, resulted in the cleavage of the cyclobutene ring to produce propyne and quinazoline (23fi) in place of the anticipated pentacyclododecane (22fi) (Scheme 20). These findings indicate that the removal of the C5-C6 double bond may be essential for the formation of pentacyclo[6.4.0.0 .0 0 ]dodecanes. 

Seki, K., Ohkura, K., Hiramatsu, H., Aoe, K., and Terashima, M., Acid-catalyzed photoreaction of 6-chloro-1,3-dimethyluracil top- and m-xylene Formation of novel photo-cycloadducts, 6-meth-ylene-9,11, x-trimethyl-9,11 -diaza-pentacyclo- [6.4.0.0 .0 -. 0 ] dodecane-10,12-diones and 5-methylene-9,11, x-trimethyl-9,11-diazapentacyclo [6.4.0.0 .0. 0 ]dodecane-10,12-diones, Heterocycles, 44, 467, 1997. 

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