Chloro-l,2-hexadiene

To a large bottle are added 116.5 gm (1.0 mole) of 3-chloro-l-hexyne, 20.0 gm (0.20 mole) of cuprous chloride, 16.0 gm (0.30 mole) of ammonium chloride, 10 ml of concentrated hydrochloric acid, 50 ml of water, and 0.6 gm of copper bronze. The bottle is sealed and shaken at room temperature for 14 days. The organic layer is separated, dried over potassium carbonate, and fractionally distilled through a glass-helix-packed column to afford 61.0 gm (52%) of nearly pure l-chloro-l,2-hexadiene, b.p. 54°-57°C (50 mm), p5 1.4567-1.4680, 9.3 gm (8%) of 3-chloro-l-hexyne, and some polymeric material. Shorter periods of reaction give lower yields. The product is purified as described for bromopropadiene. 

A simple synthesis of a glycoside of DL-daunosamine has been devised by Matsumoto and his co-workers. In this approach 1-chloro-l, 4-hexadiene-3-one (77, obtained from crotonyl chloride and vinyl chloride) was converted into 1,1-ethylenedioxy-4 -hexen-3-one (78). cw-Hydroxylation of 78 afforded threo-A o-lon (79). Oximation of 79 and reduction of the oxime gave a single stereoisomeric aminodiol (80) which, after treatment with methanolic hydrogen chloride, yielded methyl a-DL-daunosaminide (74, R = H, R = Me) in 84% yield. Makin and co-workers described two methods leading to both stereoisomeric 2-deoxy-DL-pentoses in the form of their diethyl acetals. In the first method, the readily available 1,l-diethoxy-3-penten-5-ol (81) was directly cri-hydroxylated furnish-... 

Hexadiene 2-Chloro-l. 1 -difluoro-3-hydroxy-5-methyl-EI0b2, 374 ( —CIF -> En)... 

Similarly, intramolecular [4 4- 2] cycloaddition of unactivated dienynes is also catalyzed and dramatically accelerated by low-valent rhodium complexes, e.g., Wilkinson s catalyst [chloro-tris(triphenylphosphane)rhodium] and phosphite analogs, under mild conditions46. Thus, ( , )-l-(2-propynyloxy)-2,4-hexadiene (3, Z = O) and similar dienynes, with 5 mol% of chlorotris(tri-phenylphosphane)rhodium in 2,2,2-trifluoroethanol for 30 minutes at 55 C. give up to quantitative yield of the cycloadducts with excellent to complete diastereoselection. According to control... 

If there is only enough electrophilic reagent to add to one of the double bonds, it will add preferentially to the more reactive double bond. For example, in the reaction of 2-methyl-l,5-hexadiene with HCl, addition of HCl to the double bond on the left forms a secondary carbocation, whereas addition of HCl to the double bond on the right forms a tertiary carbocation. Because the transition state leading to formation of a tertiary carbocation is more stable than that leading to a secondary carbocation, the tertiary carbocation is formed faster (Section 4.4). So in the presence of a limited amount of HCl, the major product of the reaction will be 5-chloro-5-methyl-l-hexene. 

Methyl propargyl ketone, 193 - (48) 5-Chloro-3-hexen-l-yne and 5-bromo-3-hexen-l-yne, 193 - (49) 4,5-Hexadien-2-yn-l-ol, 194 -(so) l-Phenylthio-3-methyl-l,2-butadiene, 195... 

Pentamethylenevinylidene carbene has been generated by base catalyzed 7-elimination of HCl from 1-chloro-l-ethynylcyclohexane using dicyclohexyl-18-crown-6 or 18-crown-6 as phase transfer catalyst. This unsaturated carbene has been trapped successfully by styrene (40%, see Eq. 4.16), 2,5-dimethyl-2,4-hexadiene (36%), and iso-prene (32%) [26]. 

Cyasorb UV-9. 2-Hydroxy-4-methoxybenzophenone and Oxybenzone, 79 Cyasorb UV-24, 2,2 -Dihydroxy-4-methoxybenzophenone or Dioxybenzone, 432 Cyasorb UV-531. 2-Hydroxy-4-(octyloxy)benzophenone, 134 Dalbergin. 6-Hydroxy-7-melhoxy-4-phenylcoumarin, 100 Dastib 242. 2-Hydroxy-4-(2-elhylhexyloxy)benzophenone, 135 Dehydrogriseofulvin. 7-Chloro-2, 4,6-trimethoxy-6 -methylspiro[benzofuran-2(3H),l -[2,5]cyclo-hexadiene-3,4 -dione, 458 Diethylene glycol. 2,2 -Oxybisethanol, 134, 507 Diglycol. Diethylene glycol, 507... 

Sorbicillin. l-(2,4-Dihydroxy-3,5-dimethylphenyl)-2,4-hexadien-l-one, 820 Sordidone. 8-Chloro-5,7-dihydroxy-2,6-dimethylchromone, 860 Sordidone dimethylether. 8-Chloro-5,7-dimethoxy-2,6-dimethylchromone, 860 Sotetsuflavone. 5,7,4, 5",4" -Pentahydroxy-7"-methoxy-3, 8"-biflavone, 927 Sotetsuflavone pentaethylether. 5,7,4 5",4" -Pentaethoxy-7"-methoxy3, 8"-biflavone, 927... 

Di-/i-chloro-bis(7)4-1,5-cyclooctadiene)dirhodium(l), [RhCl(l,5-C8Hi2)]2, has been prepared in 60% yield by reducing rhodium trichloride hydrate in the presence of excess olefin in aqueous ethanol.1 In the present preparation the yield has been greatly increased (to 94%). Two related complexes, [RhCl(l,5-C6Hio)]22 and [RhCl(C6H12)2]2, are similarly prepared in high yield from 1,5-hexadiene and 2,3-dimethyl-2-butene, respectively. 

A versatile method for the preparation of allyl complexes of transition elements involves addition of allyl halides or acetates to low oxidation state coordinatively unsaturated, or potentially unsaturated, complexes (214). A few attempts have been made to extend the method to halogenopentadienes. l-Chloro-5-phenyl-2,4-pentadiene adds to Pd2(dba)3 (dba = dibenzoylac-etone) to give the >/3-pentadienyl complex 61 [Eq. (30)] (215). A similar palladium complex has also been obtained from PdCl2, and 2,5-dimethyl-2,4-hexadiene in isopropanol (216). 

Mo(CH3CN)3(CO)3 reacts with allyl chloride to form MoCl( /3-C3H5)-(CH3CN)2(CO)2 (214). 1-Bromo- and l-chloro-2,4-hexadienes give analogous f 3-pentadienyl complexes (219). 

The product ratios observed for additions between allene and chlorotri-fluoroethylene or l,l-dichloro-2,2-difluoroethylene 126>, 85 15 in favor of the 3-chloro isomer and 95 5 for the 3,3-dichloro adduct, can t be interpreted unambiguously. If both adducts in a set stem from a common type of intermediate, then the product ratios indicate how different that intermediate is from the sorts of diradicals implicated in cydoadditions between, say, l,l-dichloro-2,2-difluoroethylene and the 2,4-hexadienes 16J. But the two adducts may arise throu gh completely independent, dissimilar reaction mechanisms. 

Starting from ( + )-8a-cyano-octahydro-2(l/f)-naphthalenone oxime, the corresponding (2/ ,4a/ ,8a.V)-2-chloro-2-nitmso derivative was prepared and employed in the cycloaddition with (2 , 4 )-2,4-hexadiene. The dihydro-1,2-oxazine 1 was obtained in good yield, but with only 39% ee. The configuration at C-6 was established as S, by correlation with known compounds40. 

Reaction of ozone with a double bond is not surprisingly a function of the nucleophilicity or electron density of the double bond. Therefore, in ozonolysis of octamethylsemibullvalene (122) as well as for hexamethylbicyclo[2.2.0]-2,5-hexadiene and octamethyltricyclo-octadiene the diozonides, e.g. 123, are formed as the major product (equation 33). On the other hand, for hexachlorobicyclopentadiene (124), hexachlorobicycloheptadiene and 2-chloro-3-methyl-l,3-butadiene2i attack takes place at the nonchlorinated double bond only to form the ozonide 125 (equation 34). 

Other radicals could be used to give the functional oligomer, such as 2-chloro-2-propenol, 2,4-hexadien-l-ol [142], and 3-methyl-3-buten-l-ol [143] (yield of reaction is 20%) (Scheme 22). 

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