Bicyclo 2,2-dichloro

This ether wash may be combined with the main neutral fraction and distilled to obtain 29-30 g. (33-34%) of 2-(dichloro-methylene)bicyclo[3.3.0]octane, b.p. 53-56° (01 mm.), n25d 1.5179-1.5182 (pure by gas chromatography) (column as in Note 8, 125°, retention time 4 minutes). 

Lead tetraacetate, oxidation of a hydrazone to a diazo compound, 50, 7 Lithio ethyl acetate, 53, 67 Lithium, reductions in amine solvents, 50, 89 Lithium aluminum hydride, reduction of exo-3,4-dichloro-bicyclo-[3.2.l]oct-2-ene to 3-chlorobicyclo[3.2.l]oct-2-ene, 51, 61... 

Dimers with a 1,2-bismethylenecyclobutane structure were obtained from 585 [240], 590 [238], 591 [241], 592 [242], 593 [243] and from the pinene derivative 597 [244]. The interception of 592 by 1,3-diphenylisobenzofuran (DPIBF) afforded two diastereomeric [4+ 2]-cycloadducts [245], Bicyclo[5.1.0]octa-3,4-diene (594) was generated by /3-elimination and trapped by sodium pyrrolidide because of the question of the extent to which the corresponding bicyclooctyne is formed in addition to 594 [184], Liberated by /3-elimination from ll,ll-dichloro-l,6-methano[10]annulene in... 

An example of the vinylogous reactivity is the reaction of 52 with cyclopentadiene (Tab. 14.9) [77]. Rhodium(II) acetate-catalyzed decomposition of 52 in dichloro-methane, yields a 2 1 mixture of the bicyclic system 53 derived from the [3-1-4] cycloaddition, and the bicyclo[2.2.1]heptene 54 resulting from electrophihc attack at the vinylic position followed by ring closure. When Rh2(TFA)4 is used as the catalyst, bicy-clo[2.2.1]heptene 54 becomes the dominant product, while the reactivity of the vinyl terminus is suppressed using a hydrocarbon solvent as observed in the Rh2(OOct)4-cat-alyzed reaction in pentane, which affords a 50 1 ratio of products favoring the [3-1-4] cycloadduct 53. 

The successful application of the Doering-Moore-Skattebol reaction to the preparation of relatively small-ring heteroorganic cycloallenes is of recent origin. A specific example is provided by 6,6-dichloro- and 6,6-dibromo-3-oxa-bicyclo-[3.1.0]hexane, respectively, which yield l-oxa-3,4-cyclohexadiene when treated with n-butyllithium at low temperatures. The formation of the allene was proven by various trapping experiments [89],... 

Whereas the parent difluoro-vinylcyclopropane isomerizes to difluorocyclopentene under pyrolysis conditions, the corresponding alkyl compounds also lead to acyclic dienes. The activation energy for the difluoro-vinylcyclopropane isomerization is practically identical with that observed for the unsubstituted hydrocarbon [211, 212], If the alkyl group is oriented cis to the vinyl substituent, only dienes are isolated, and the process occurs at much lower, temperatures. Presumably these stereoisomers rearrange by a different mechanism (a 1,5-homodienyl hydrogen shift [213]). When the dichlorocyclopropane XVII is subjected to flash vacuum pyrolysis it isomerizes to 9,9-dichloro-bicyclo[5.3.0]dec-l(7)-ene [214],... 

C12RuC7Hk, Ruthenium(II), (V-bicyclo-[2.2.1]hepta-2,5-diene)dichloro-, 26 250 C12RuC H 2, Ruthenium(II), dichloro(V-cy-cloocta-1,5-diene)-, 26 253... 

Dichloro-phenyl)-1 -[2-(3-isopropoxy-phenyl)-acetyl]-piperidin-3-yl -ethyl)-4-phenyl-1-azonia-bicyclo[2.2.2]octane chloride, C37H45CI3N2O2,... 

Thiiranes can be formed directly and stereospecifically from 1,2-disubstituted alkenes by addition of trimethylsilylsulfenyl bromide, formed at -78 C from reaction of bromine with bis(trimethylsilyl) sulfide (Scheme 7).12 A two-step synthesis of thiiranes can be achieved by addition of succinimide-A/-sulfe-nyl chloride or phthalimide-A -sulfenyl chloride to alkenes followed by lithium aluminum hydride cleavage of the adducts (Scheme 8).13 Thiaheterocycles can also be formed by intramolecular electrophilic addition of sulfenyl chlorides to alkenes, e.g. as seen in Schemes 914 and 10.13 Related examples involving sulfur dichloride are shown in Schemes 1116 and 12.17 In the former case addition of sulfur dichloride to 1,5-cyclooctadiene affords a bicyclic dichloro sulfide via regio- and stereo-specific intramolecular addition of an intermediate sulfenyl chloride. Removal of chlorine by lithium aluminum hydride reduction affords 9-thiabicyclo[3.3.1]nonane, which can be further transformed into bicyclo[3.3.0]oct-1,5-ene.16... 

The (2 + 2) cycloaddition reactions of ketenes with alkenes are synthetically useful routes to cyclobutanones. Ketenes are particularly useful due to the low steric hindrance at the carbonyl carbon. An example is the reaction of dichloro-ketene with cyclopentadiene which, after reductive dechlorination of the product, gives bicyclo[3.2.0]hept-2-en-6-one (Expt 7.25). 

Dichloro-2-(5-methoxyhept-l-yl)bicyclo[3.2.0]heptan-7-one (5 g), is dissolved in 100 ml of ether and transferred to a 500 ml, round-bottomed flask. An excess of diazomethane is generated in situ by reacting N-methyl-N-nitroso-p-toluene sulfonamide (60 g) with potassium hydroxide in ethanol. 

The diazomethane is allowed to react for 50 min, after which time acetic acid is added to destroy any remaining diazomethane. The solution is extracted with ether and dried over anhydrous sodium sulfate and yields the crude 6,6-dichloro-2-(5-methoxyhept-l-yl)bicyclo[3.3.0]octan-7-one as an orange oil. 

Dichloro-2-(5-methoxyhept-l-yl)bicyclo[3.3.0]octan-7-one (45.9 g) is added to a 100 ml, round-bottomed flask fitted with a condenser. Powdered zinc metal (92 g) and glacial acetic acid (312 ml) are added to the flask and... 

The previously reported4 procedure, which is a technique of general utility, involves the reaction of dichloro(l,5-cycloocta-diene)palladium(II) with a solution of sodium bromide in acetone. The following procedure gives comparable yields and eliminates the need for the preparation of the dichloro intermediate. Bicyclo[2.2.1]hepta-2,5-diene (2,5-norbornadiene) may be substituted in the following procedure for the 1,5-cyclooctadiene to yield (bicyclo[2.2.1]hepta-2,5-diene)dibromopalladium(II). 

Uemura and co-workers have demonstrated that reaction of 1,5-cyclooctadiene with antimony pentachloride in carbon tetrachloride at —20 ° leads to a mixture of the epimeric dichloro bicyclo[3.2.1 ]octanes 49 and 50.83 Through dehydrochlorination and Ag+-promoted ionization, a bicyclo[3.3.0]octenyl acetate was produced (Scheme 16). 

The oxa-thiacrown ether having bicyclo[2.2.2]octane units was prepared from a mixture of dichloro sulfides 28 and 29 <2002CHE261>. The reaction of the mixture with diethylene glycol by a high-dilution method led to the formation of only one stereoisomer of 30 in 40% yield (Scheme 3). 

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