Diene Reactions with Dicyclohexenyl

Reactions involving electron transfer. VII. Use of intramolecular reactions as a test for anion radical intermediates

“…After the resulting solution had been stirred at -40°for 30 min, a solution of 4.07 g (48 mmol) of the aldehyde 16 in 15 ml of Et2Ü was added, dropwise and with stirring. The resulting solution was stirred at -40°for 15 min and poured into cold aqueous 1 M HCI and extracted with Et20. The ethereal extract was washed successively with aqueous NaHCQ3 and with aqueous NaCl and then dried and concentrated to leave 6.51 g (74%) of the crude ketol 17 as a low-melting solid.…”

Ring enlargement reaction of phenylmethoxycyclopropenone. Regiospecific mass spectrometric carbon monoxide extrusion in phenylmethoxycyclobutenedione

“…,a 30 min, 20® 6 + H2180, dioxane, HC1 -6 1. H20, dioxane, 30 min, 20°7 "'0 --6-'(), -v 2, CH2N2, ether ,+ [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] ion, 90 ± 5% of which was lost in the P -CO+ ion. Alternatively, statistically labeled 7, dissolved in H20dioxane, for 30 min at room temperature followed by methylation afforded 5 in which the parent and P -CO+ ions contained approximately the same amount of only 50% of the 180 label in the P -CO+ ion if the oxygen at these positions was lost.…”

“…Recrystallization from hexane afforded 4 -(2,6 -dimethylphenylimino) -3 -methoxy -2phenylcyclobuten-l-one (5) as yellow crystals. The gross structural features of 5 were established by hydrolysis to phenylmethoxycyclobutenedione4 (6) and 2,6-dimethylaniline, isolated as the hydrochloride, in 80% yield.…”

Synthesis of the Indole Nucleus

“…The failure to detect and obtain both isomers is no doubt a problem of analysis and separation. When 2-(m-toluidino)cyclohexanone (495) was heated in cellosolve containing magnesium chloride and aniline, there was obtained a 3 : l mixture of 7-methyl-l,2,3,4-tetrahydrocarbazole (496) and 5-methyl-l,2,3,4-tetrahydrocarbazole (497) from which the former crystallized readily, but the latter could not be separated in the pure state either by crystallization or chromat~graphy'~~ (Eq. 160 Since all of the above examples of meta-substituted anilines contained either an alkyl, an alkoxy group, or an halogen atom as the substituent, all of which are known to favor electrophilic substitution at the position in the aromatic ring para to themselves, this directive effect in the Bischler reaction supports the view that the ring closure occurs by an ionic rather than free radical mechanism.…”

“…499 this is not unreasonable as the first step. This mechanism would offer an explanation for the observation that as the bulk of the substituent R2 on the nitrogen of the B-aminocrotonate 594 or of R' of 614 (Scheme 60) increases, the proportion of the 7-substituted indole 620 488 However, because @-amino crotonic acid esters possess the enamine rather than the imine structure500 and since enamines are known to react as electrophilic species at the terminal carbon of the enamine and also because many reactions of quinones appear to occur by a Michael type addition to the olefinic double bond ;4s1* 495 Steck's scheme is unlikely. A recent report describes work which is believed to provide evidence that the mechanism of the Nenitzescu indole synthesis does not involve the condensation of the amino group of an enamine with the carbonyl moiety of a p-benzoquinone as its first…”