
%0 Journal Article
%A Collin, PJ 
%T Bridgehead <sup>1</sup>J(<sup>13</sup>C-H) values in 1,8-disubstituted 1a,2,7,7a- Tetrahydro-1,2,7-metheno-1H-cyclopropa[b]naphthalene compounds
%J Australian Journal of Chemistry
%D 1972/02/01
%V 25
%N 2
%P 425-426
%K 
%R https://doi.org/10.1071/CH9720425
%U https://www.publish.csiro.au/paper/CH9720425 
%X The value of the bridgehead 13C-H coupling constant tends to increase as the degree of &quot;strain&quot; increases in cyclic hydrocarbons. Thus, in the highly &quot;strained&quot; 1,3-dimethyltricyclo[1,1,1,04,5]pentane, the bridgehead J(13C-H) value is 212 Hz1 and in the slightly less &quot;strained&quot; bicyclo[l,l,0]butane, the bridgehead 13C-H coupling is c. 200 Hz.2 In both of these compounds the bridgehead proton is attached to two three-membered rings. When the bridgehead proton is common to two four-membered rings, such as in cubane and bicyclo[l,l,l]pentane,2 the coupling constant is c.160 Hz. In &quot;unstrained&quot; systems such as methane and cyclohexane the value is c.125 Hz. 
