Bornene

Submitted by Robert H. Shapiro and J. H. Duncan Cheeked by Robert Czarny and Robert E. Ireland 

Camphor tosylhydrazone is prepared in the following manner. To a 1-1. one-necked round-bottomed flask are added 44 g. (0.24 mole) of p-toluenesulfonylhydrazide, 31.6 g. (0.20 mole) of camphor, and 300 ml. of 95% ethanol. One milliliter of concentrated hydrochloric acid is added, and the flask is fitted with a reflux condenser. The solution is heated under reflux for 2 hours. The resulting solution is cooled in an ice bath, and the colorless needles are collected by suction filtration and dri( d in air (Note 11). Recrystallization from ethanol yields 50 g. (73 ), ) of [)ni( camphor tosylhydrazonc, m.p. 163-164°. 

Anhydrous ether available from Mallinckrodt Chemical Works can be used without further drying. 

This prevents clogging of the funnel during the subsequent addition of methyllithium solution. 

Methylhthium available from either Foote Mineral Company or Alfa Inorganics, Inc. can be used without further purification. The checkers used 137 ml. of a 1.85Af solution. 

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Since the solvent is never completely removed at any time prior to final distillation of the product, the accumulation of higher boiling hydrocarbons results if petroleum ether is used. As a result the fore-run of the final distillation will be larger, and the yield of 2-bornene will be reduced. The pentane was distilled to assure the removal of any higher boiling impurities. 

When the temperature of the bath reaches 140-143°, the heating lamp is turned directly on the U-tube, and the receiver is changed to collect the 2-bornene. 

Bornene has been prepared from the reaction of 2-bromo-bornane-3-carboxyIic acid with aqueous sodium bicarbonate,6 by pyrolysis of isoborneol methyl xanthate,7 and by the j8-elimination of hydrogen chloride from bornyl chloride with sodium alkoxides in various solvents.2... 

The ozonide of 2,3-diphenyl-2-bornene can be prepared by photosensitized addition of oxygen to the corresponding epoxide (313), as shown in equation 103. The structure of product 314 was determined by single-crystal XRD crystallographic analysis. It should be pointed out that both 302 and 314 have Oe envelope conformation for the 1,2,4-trioxolane... 

Rule 6. For a double bond within the ring, only one prefix number is necessary — that is, the lower-numbered carbon to which the double bond is attached — e.g., 2-norbomene, 2-bornene. 

Ranganathan also reports iodine azide addition to camphene in MeCN at —10 °C to give two compounds 288 the minor component is (5 X = CHI) and the major component is probably (199 X = N3, Y = CH2I) and not the proposed unstable (199 X = I, Y = CH2N3). 2-Bornene yields (201) and the endo-azide (202) as major products, together with a small amount of the isomeric exo-azide.287... 

Borabicyclo[3.3.1Jnonane (9-BBN), 31 Boric acid, 32 2-Bornene, 419 Boronobenzoic acid, 32 Boron oxide, 32 Boron tribromide, 33-34 Boron trichloride, 34-35 Boron triiluoride etherate, 7, 9, 35-36, 40, 124, 160, 161, 182, 229, 230, 430, 438 Boron trifluoride etherate—Acetic anhydride, 36-37... 

Shapiro and Duncan01 have described use of the method for the synthesis of 2-bornene (6) from camphor tosylhydrazone (5). 

A new hydroxycamphene (566) has been found in two species of chrysanthemum. [2- H J-2-bornene can be made by the action of BuLi on camphor tosylhydrazone in hexane followed by DjO quench. In ether proton abstraction from solvent occurs before work-up. However, with less hindered hydrazones, deuterium incorporation is much reduced since the vinyl anion can apparently act as the base (B) in (567) and so capture a proton. ... 

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