Diazoalkanes, cycloaddition

Danishefsky s diene 154 DBFOX 232 dendrimers 229 DPT calculations 308 diacetone glucose derived-titanium(IV) 178 diastereoselectivity 216 diazo compounds 242 diazoalkane cycloadditions 278 diazoalkanes 213, 231 (R,R)-4,6-dibenzofurandiyl-2,2 -bis(4-phenylox-azoline) 250... 

In a novel total synthesis of the tricyclic sesquiterpene (—)-longifolene, an intramolecular diazoalkane cycloaddition to a cyclohexadienone ring followed by thermal ring contraction of the resulting pyrazoline gave the tricychc vinylcyclo-propane 261 and this constitutes the key steps in this synthesis (314) (Scheme 8.63). The interesting features of this sequence are the separation of dipole and dipolarophile by five atoms and the formation of a seven-membered ring in the cycloaddition step. 

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