5-methylenebicyclo octene

Bicyclo[2.2.2]-2-octene Bicyclo[3.2.1]-2-octene 2-Methylenebicyclo[2.2.1 ]heptane 2-Methylbicyclo[2.2.1 ]-S-heptene ... 

Methylenebicyclo[2.2.2 ]octane 5-Methylbicyclo[2.2.2]-2-octene 2-MethyIene-3-methylbioyclo[2.2.1]heptane 2-Methylene-1-me thylbicyolo[2.2. l]heptane 3 -Methylene-1 - methylbio yolo[2.2.1 ]heptane 2-Methyl-cis-bicyelo[3.3.0]octane (CsHie) 2-Methyl-ci -bicyelo[3.3.0]-2-ootene... 

In this series we may find, besides the methylated homologs of the C8Hi2 hydrocarbons already described, some new products of cycle expansion. The vapor-phase silicophosphoric acid-catalyzed reaction of 2-methylenebicyclo[2.2.2]octane (18) at 195° produces the double-bond isomer (1 ) and a mixture of 1-methyl-, 2-methyl-, and 3-methylbicyclo-3.2.1[octenes] (21, 22, and 23) (Fig. 5) through seemingly parallel reactions (Fig. 6) 15, 16). 

In fact, whenever the primary carbonium ion is formed from the proper substrate, ring expansion is observed this is the case in the acid-catalyzed dehydration of 2-hydroxymethylbicyclo[2.2.1]heptane (23), producing a mixture of 2.5% methylenebicyclo[2.2.1]heptane (7), 87% bicyclo[3.2.1]-2-octene (5), and 10% bicyclo[3.3.0]-2-octene (6) and in the nitrous acid deamination of 2-aminomethylbicyclo[2.2.1]-heptane to bicyclo[3.2.1]- and bicyclo[2.2.2]octanols 30). 

In hindered or strained systems the yields are more variable. Thus, the yield of methylene product from 1-chloro-l-methyl-2,2-diphenylcyclopropane was only 39%. ° In a series of methylenecyclopropanes containing a bicyclic system with aryl bridgehead substituents, the yields in some cases were very poor (Table 1). In the absence of such substituents, however, the yields are generally very good. Thus, a 78% yield of pure 7-methylenebicyclo[4.1.0]heptane (13, n = 2) and a 85% yield of pure c/5-9-methylenebicyclo[6.1.0]nonane (13, n = 6) were obtained from the 1-chloro-l-methylcyclopropanes 12 derived from cyclohexene and (Z)-cyclo-octene, respectively. ... 

Reactive Intermediates.—Additions of dichlorocarbene to cyclo-octatetraene, bicyclo-[6,l,0]nona-2,4,6-triene, iV-ethoxycarbonylazepine, cycloheptatriene, and related compounds have been studied, and the stereochemistry of the products explained in terms of approach of the carbene from the least hindered direction, e.g. cyclo-octatetraene gave only one bis-adduct (172). Treatment of cyclo-octene with 1,1-dichloroethane and n-butyl-lithium gave 9-chloro-9-methylbicyclo[6,l,0]nonane, which was converted into 9-methylenebicyclo[6,l,0]nonane using potassium t-butoxide this procedure has been developed into a general preparation of methylene-cyclopropanes. ... 

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