5633 Table I. Relative Reactivities of Alkenes toward Phenylbromocarbene, 25' (a) (kT&fdki)BaseC
TMEblolefini
Case
a
(b) (kTME/ki)hud
(C) (kTdki)erown'
1.74 f 0.042 4.44 f 0.182 8.34 f 0.042 17.5 & 0.82 5.0 & 0.36
1.72f 4.11 f 0.142 8.24f 17.1 f. 0.42 4.8f
-~
1 2 3 4
TME-trimethyleth ylene TME-isobutene TM E-cis- butene TME-trans-butene TME-isobutene
5h
1 . 2 8 f 0.093 1 . 6 5 f.0.2170 5.79 2k 0.112 11.3 & 1.64 2.6 0.13
+
-
Relative reactivities were calculated in the standard' man11er,~-7 and mean values are reported. Errors are average deviations from the means of n (subscript) experiments. The analytical methods (quantitative nmr) are fully described in ref 5 and 7. b TME = tetramethylKO-t-Bu.6 d 3a hv.6 e 2a KO-r-Bu 18-crown-6, this work. f Single experiment. The nmr integrals were preethylene. c 2a 1.83, this work, h Phenylchlorocarbene was used; C1replaces Br throughout. cise to
