Selective alkylation of cyclopentadiene
Provided is a process for the mono-alkylation of cyclopentadiene, utilizing a cyclopentadiene magnesium halide and a metal salt of an alkyl or aryl sulfonate as co-reactant with an alkyl halide alkylating reactant. The process provides facile methodology for the mono-alkylation of cyclopentadiene, with conversions as high as about 96 percent and selectivity for mono-alkylation (over higher level alkylation, such as di- or tri-) as high as about 99%.
1. A process for preparing a compound of Formula (I):
wherein R is chosen from C 1 -C 8 alkyl, the process comprising contacting
(A) the reaction product of (a) a compound of the formula:
wherein X is chloro or bromo, and (b) a compound of the formula MO 3 SR′, wherein M is chosen from alkali metals or alkaline earth metals, and R′ is C 1 -C 8 alkyl, phenyl, or phenyl substituted with one or more C 1 -C 8 alkyl groups or phenyl; and
(B) a compound of the formula R-X′, wherein X′ is chosen from chloro, bromo, iodo, alkyl-sulfonate, or aryl-sulfonate, to produce the compound of Formula (I).
2. The process of claim 1 , wherein R is isopropyl.
3. The process of claim 1 , wherein R is sec-butyl.
4. The process of claim 1 , wherein M is chosen from sodium, lithium or potassium.
5. The process of claim 1 , wherein R′ is 1,3,5-trimethylphenyl.
6. The process of claim 1 , wherein R′ is trifluoromethyl.
7. The process of claim 1 , wherein R′ is p-methylphenyl.
8. The process of claim 1 , wherein the compound of Formula (I) is produced with a conversion of at least about 70 percent.
9. A compound of the formula
wherein R′ is chosen from C 1 -C 8 alkyl, phenyl, or phenyl substituted with one or more C 1 -C 8 alkyl groups or phenyl.
10. The compound of claim 9 , wherein R′ is chosen from 1,3,5-trimethylphenyl, trifluoromethyl, or 4-methylphenyl.
11. The compound of claim 9 , wherein R′ is 4-methylphenyl.
12. The compound of claim 9 , wherein R′ is 1,3,5-trimethylphenyl.
13. The compound of claim 9 , wherein R′ is trifluoromethyl.