H–D exchange of 1-methylcycloalkenes in dilute acid at elevated temperatures

. Can. J. Chem. 66, 454 (1988).To assess the influence of the conformation of the cyclohexanonc moiety in bicyclo[3.2.l]octan-2-ones on the reactivity for p-enolate rearrangement, the behavior of three derivatives under typical hon~oenolization conditions has been examined for comparison with 3.3-dimethylbicyc~o[3.2.l]octan-2-one (I), which was known to be snloothly converted to the [3.3.0] isomer 2. For this purpose, e1~do-3-tert-butyl-e,~o-3-methylbicyclo[3.2.l]octan-2-onc (8), elldo-9-tert-butyl-exo-9-methyl-exotricyclo[5.3.1 .0',6] undecan-8-one (9), and 9,9-dimethyl -elldo-tricyclo[5.3.1 .0',6] undecan-8-one (10) were prepared and treated with t-BuO-It-BuOH at 2 185OC for prolonged periods. Each is much less reactive than 1. The relative orientations of the carbonyl groups with respect to the sites for p-enolizhtion were determined by molecular mechanics (MM2) calculations. ' H /~H exchange in 9 and 10 was also examined under strongly basic conditions at 185OC. Dans le but d'Cvaluer I'influence de la conformation de la portion cyclohexanone des bicyclo[3.2.l]octanones-2 sur la rCactivitC conduisant a une transposition P-Cnolique, on a examin6 le comportement de trois dCrivCs dans des conditions d'homoCnolisation pour comparer avec le comportement de la dimCthyl-3,3 bicyclo[3.2.l]octanone-2 (I) qui se transforme facilement en son isomkre [3.3.0] (2). A ces fins, on a prCparC la tert-butyl-3-endo mCthyl-3-exo bicyclo[3.2. lloctanone (8), la tert-butyl-9-endo mCthyl-9-endo tricyclo[5.3.1.0'~6]und~canone-8-eso (9) et la dimCthyl-9,9 tricyclo[5.3

Section: 'H/'h Exchange Experimentssupporting

confidence: 91%

“…90". With resolution enhancement, the methyl absorption for the 48-and 96-h samples clearly consisted of three components arising from CHID, CHD', and CD3 species (14), establishing that extensive exchange occurred at the a-methyl site. The 'H-induced isotope effect on the deuteriomethyl shielding is 18 ppb.…”

Section: 'H/'h Exchange Experimentsmentioning

confidence: 94%

¹³C magnetic resonance studies 133. An examination of the effect of conformation on β-enolization in some bicyclo[3.2.1]octan-2-ones

Clements¹,

Klinck²,

Peiris³

et al. 1988

“…The magnitude of this splitting in simple cyclic and acyclic dienes varies dramatically with the dihedral angle defined by the four vinylogous carbons (ref. 22 and footnote 3). MNDO calculations canied out for Eand 2-4 predict the most stable conformers to be twisted s-cis in both cases; the calculations for E-4 predict a twist angle of 60.8" and a HOMO-SHOMO splitting of 1.1 eV, while those for 2-4 predict a twist angle of 79" and a splitting of 0.5 eV.…”

Section: Resultsmentioning

confidence: 98%

Cyclobutene photochemistry. Involvement of carbene intermediates in the photochemistry of alkylcyclobutenes

Clark¹,

Leigh²

1988

. Can. J. Chem. 66, 1571 (1988). The photochemistry of 1,3,3,4-and 1,3,4,4-tetramethylcyclobutene has been investigated in pentane solution with monochromatic far ultraviolet (185, 193, and 214 nm) light sources, as well as in methanol solution with 214-nm excitation. Photolysis of each of the two isomeric cyclobutene derivatives results in competitive electrocyclic ring opening (yielding mixtures of stereoisomeric dienes in each case), fragmentation to yield propyne and methyl-2-butene, and isomerization to the other cyclobutene isomer. Quantum yields for product formation with 185-nm excitation have been measured in each case by cyclooctene actinometry. The occurrence of the interconversion process is offered as evidence for the intermediacy of cyclopropyl carbenes in the photochemistry of simple cyclobutenes in solution. On the basis of the known chemistry of carbenes of this type, their intermediacy in cyclobutene photochemistry may account at least partially for the formation of the formal ( 2 r + 2 r ) cycloreversion products from photolysis of simple cyclobutene derivatives. deux dCrivCs cyclobuttnes isomtres conduit une ouverture de cycle Clectrocyclique (conduisant dans chaque cas a des melanges de diknes stCrtoisomtres) qui est en compCtition avec une fragmentation conduisant au propyne et au mCthyl-2 butkne-2 et avec une isomCrisation conduisant a l'autre isomkre cyclobuttne. Utilisant I'actinomCtrie du cycloocttne et operant a 185 nm, on a mesurt les rendernents quantiques pour la formation des produits. Le fait que I'on observe le processus d'interconversion est propost comme preuve de la prCsence de carbtnes cyclopropyles comme intermkdiaires dans la photochimie des cyclobuttnes simples, en solution. En se basant sur la chimie connue des carbenes de ce type, on peut supposer que leur presence comme intermkdiaires peut expliquer, au moins en partie, la formation des produits de la cyclorCversion formelle (27r + 27r) de la photolyse de dCrivCs cyclobutknes simples.[Traduit par la revue]

“…J. Chem. 66, 2309(1988.On a utilisC une mCthode modifiee impliquant une temptrature ClevCe et de l'acide dilut pour synthktiser le phtnyltthened2-2,2 (cc styrbne-d2-2,2 n) (lb), le phCnyl-2 propbne-d5-l,l,3,3,3 (c a-trideutCromtthylstyrbne-ds-2,2 n) (26) et le phtnyl-1 propkne-d-2-(E) ( e P-mkthylstyrkne-d2-d-trans,) (36) 2 partir respectivernent du phCnyltthbne (~styrbnen) (la), du phCnyl-2 prophe (c< a-mCthylstyrkne D) (2a) et du phCnyl-1 propkne-(E) (cc P-mCthylstyrbne-trans n) (3a). On a aussi obtenu le diphCny1-1,3 butbne-1-d4-2,2,4,4-(E) (4b) i partir du compost l a .…”

unclassified

“…To reduce the extent of , substitution (polymerization) of these substrates, a modified ' HTDA method (7,9) was used. An inert cosolvent was added to 1 "dilute" the water-insoluble substrate and the reaction mixture ' was shaken to facilitate phase transfer.…”

mentioning

confidence: 99%

Protium–deuterium exchange of styrenes in dilute acid at elevated temperatures

Timmins¹

1988

Self Cite

A modified high temperature -dilute acid method is used to synthesize phenylethene-2,2-dl ("styrene-2,2-d2") (lb), 2-phenylpropene-l,l,3,3 ,3-ds ("a-trideuteriomethylstyrene-2,2-ds") (2b), and E-1-phenylpropene-2-d ("trans-P-methylstyrene-24') (3b) from phenylethene ("styrene") (la), 2-phenylpropene ("a-methylstyrene") (2a), and E-1-phenylpropene ("trans-P-methylstyrene") (3a), respectively. The deuteriated substitution product E-1 ,3-diphenyl-1-butene-2,4,4,4-d4 (4b) is also obtained from l a . Labelled substitution products 1 ,3,3-tri-trideuteri0methyl-l-phenylindane-2,2-d~~ (Sb), 4-trideuteriomethyl-2,4-diphenyl-1-pentene-1 , 1 ,3,3,5,5,5-dlo (6b), and E-4-trideuteriomethyI-2,4-diphenyl-2-pentene-1,1,1 ,3,5,5,5-dlo (76) are obtained from 2-phenylpropene.NICK HENRY WERSTIUK et GEORGE TIMMINS. Can. J. Chem. 66, 2309(1988.On a utilisC une mCthode modifiee impliquant une temptrature ClevCe et de l'acide dilut pour synthktiser le phtnyltthened2-2,2 (cc styrbne-d2-2,2 n) (lb), le phCnyl-2 propbne-d5-l,l,3,3,3 (c a-trideutCromtthylstyrbne-ds-2,2 n) (26) et le phtnyl-1 propkne-d-2-(E) ( e P-mkthylstyrkne-d2-d-trans,) (36) 2 partir respectivernent du phCnyltthbne (~styrbnen) (la), du phCnyl-2 prophe (c< a-mCthylstyrkne D) (2a) et du phCnyl-1 propkne-(E) (cc P-mCthylstyrbne-trans n) (3a). On a aussi obtenu le diphCny1-1,3 butbne-1-d4-2,2,4,4-(E) (4b) i partir du compost l a . Utilisant le phCnyl-2 propkne, on a aussi prCparC les produits marquks suivants : tri-trideuttromCthy1-1,3,3 phCnyl-1 indane-dl 1-2,2 (Sb), trideutCromCthy1-4 diphenyl-2,4 pentbne-1-dlo-1 ,1,3,3,5,5,5 (6b) et trideutCromCthy1-4 diphCnyl-2,4 pentene-2-dlo-1 ,l,l,3,5,5,5-(E) (76).[Traduit par la revue]