ISSN:
1573-9171
Keywords:
polycyclic spirolcyclopropane-1,3'-pyrazolines-1
;
polycyclic 1,2-spiropentanes
;
1,4-spirohexanes and methylenecyclobutanes (anti-Bredt olefmes)
;
pyrolysis
;
catalytic cyclopropanation with diazomethane
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract 1-Pyrazolines1 and2 obtained by 1,3-dipolar cycloaddition of diazocyclopropane to norbornene or deltacyclene undergo dediazotization at 410–450°C to give a mixture of strained hydrocarbons, namely, spirocyclopropane-1,3'-tricyclo[3.2.1.02,4]octane (4) or spiro{cyclopropane-1,4'-pentacyclo[4.4.0.02,8.03,5.07,9]decane} (6) and isomeric tricyclo[5.2.1.02,5]dec-5-enes (5) or pentacyclo[6.4.0.02,10.03,6.09,11]dec-6-enes (7) in a 30–70% overall yield. An increase in temperature favors the isomerization of spiro hydrocarbons4 and6 to the respective unsaturated hydrocarbons5 and7. The latter undergo cyclopropanation with diazomethane in the presence of Pd(acac)2 or (PhO)3P · CuCl to afford polycyclanes9a,b or10a,b containing a spiro[2.3]hexane moiety condensed at thecis-1,4 position. Unsaturated 1-pyrazoline3 obtained from diazocyclopropane and norbornadiene decomposes at 330–370°C with elimination of cyclopentadiene to give 3(5)-vinylpyrazole in a yield up to 75%.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00699834
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