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Downstream Products

• 85624-99-3 c-4-t-butyl-c-2,c-6-dimethyl-t-1-prop-1'-ynylcyclohexan-r-1-ol 
• 85625-00-9 t-4-t-butyl-t-2,t-6-dimethyl-t-1-prop-1'-ynylcyclohexan-r-1-ol 

Relevant academic research and scientific papers

Hydrogen shifts in cyclohexylcarbenes. Spatial dependence of activating power and of primary deuterium isotope effects

The conformationally biased ketones 4-t-butyl-cis-2-methylcyclohexanone (1c) and 4-t-butyl-cis-2-trans-6-dimethylcyclohexanone (7a; and its 2,6-dideuterio derivative 7c) were converted into p-toluenesulfonylhydrazone Li salts. Thermolysis or photolysis generated putative singlet carbenes, which underwent competitive axial vs equatorial H shift (or D shift in the case of 7c) to give alkenes. Product analysis showed that a bystander Me(eq) substituent promotes a geminal H shift several times more efficiently than does a bystander Me(ax). This geometry-dependent activating power parallels behavior noted earlier for OMe and Ph bystander groups; but as Me groups are rotationally symmetric and possess no lone pair or π electrons this phenomenon cannot be attributed solely to rotameric considerations or to effects involving mobile electron clouds. For the trans-dimethylcarbenes 10a and 10c the primary deuterium isotope effect (k(H)/k(D)) for axial migration (I(ax)) was determined to be ca. 1.5 times larger than that for equatorial migration (I(eq)). This finding invalidates the common assumption that I(ax) = I(eq) and suggests that published data on deuterium isotope effects and on H(ax)/H(eq) migration selectivities need to be adjusted.