ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
On 1.2-Shift Reactions and C—H-Insertions of Acyclic Alkylidene CarbenesTwo series of acyclic terminal vinyl bromides (1…4 and 5…7) were tested in the reaction with potassium tert-butoxide as precursors of alkylidene carbenes. As expected 1 up to 4 only give 1-alkynes whereas the 2-methylated vinyl bromides 5, 6 and 7 yield 1-methylated cyclopentenes predominantly besides 2-alkynes. The formation of cyclopentenes indicates a reaction route via alkylidene carbenes and 1,5-C—H-insertion reactions, that of 2-alkynes is convincing evidence for 1,2-alkyl shift reactions in 2-methyl substituted alkylidene carbenes. The selectivity of 1,5-C—H-insertion depends on the degree of alkyl substitution of the C-5-atom. At 240°C the selectivity is 1°:2°:3° ≈ 1:54:240.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19873290107
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