selectivities of la and lb, generated from 2a and 2b with KO-t-Bu-18

5633. Table I. Relative Reactivities of Alkenes toward Phenylbromocarbene, 25' a. (a). (b). (C). Case. TMEblolefini. (kT&fdki)BaseC. (kTME/ki)hud. (kT...
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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