Indene, benzyl

A = C)Ht 13554 C HitO Indene Benzyl ethyl ether 182.6 185.0 Nonazeotrope 238... 

Indenes, 34 Indole [ 1H Indole], 10 INDOLE, 3-BENZOYL- [METI1ANONE, 1//-INDOL-3-YLPHENYL-], 8 INDOLE, 3-BENZYL- [lff-INDOLE, 3-(PHENYLMETHYL)-], 8 INDOLE, 5-CARBOETHOXY-2-METHYL-] 17/-1NDOLE-5-C ARBOXYLIC ACID, 2-METHYL, ETHYL ESTER], 72 Indole, S-carlioethoxy-2-methyI-3-niethyl-thio-11H Indole-5-carboxyhc acid, 2-methyl-3-(methylthio)-, ethyl ester, 73... 

The general feature of alkylation reactions at a carbon atom is that they can be achieved under sonication using solid bases even in apolar solvents. The advantage is that side reactions are generally minimised. Deprotonation occurs readily on a benzylic position in the presence of aqueous sodium hydroxide, as shown with indene (Eq. 3.21) [117]. A quantitative yield of the alkylated product can be obtained using sonication in the presence of a PTC. It was suggested that alkylation of cyclopentadiene or indene by secondary or tertiary alkyl halides in the presence of potassium hydroxide and Ali-quat occurred via a SET process [118]. 

From a mechanistic point of view, it can be envisaged that this reaction proceeds via the desired benzylated pentanedione intermediate 14f. The subsequent intramolecular Friedel-Crafts alkylation of the electron-rich arene results in the quaternary benzyl alcohol II, which readily eliminates water to give the highly substituted indene 16 (Scheme 14). 

In the preceding cyclization, one concern is the behavior of intermediate 24 if its benzyl cation is replaced with a tertiary cation to avoid forming a tertiary carbon, the 1,2-aryl migration of this intermediate would be unlikely to occur. When this cyclization was extended to 2,2-dimethyl(o-ethynyl)styrene 26, the 2-alkenyl-lH-indene product 28 [16] was obtained in 76% yield, as depicted in Scheme 6.14. In this transformation, the alkenyl double bond of the 3,5-dien-l-ynes is cleaved and a... 

In this cyclodecarbonylation reaction, a ketene species is unlikely to be the reaction intermediate as added alcohols produce no esters. As shown in Scheme 6.26, the ruthenium acyl species 72 is likely to be the intermediate [25], which is prone to decarbonylationto give ruthena-cyclohexadiene 73 this species undergoes subsequent reductive elimination to form 2H-indene. Addition of proton or Ru to species 74 generated the benzylic cation 75, which after a 1,2-aryl shift gave the observed products. 

Whereas, in the presence of PtBr2, internal alkynes of type 127 were cleanly transformed to vinyl naphthalenes (129), similar terminal alkynes were converted primarily to indenes (131). The authors quickly discovered that the observed C—H insertion reaction is very substrate specific. Only tertiary benzylic C—H bonds could be... 

Recently, a general catalytic method forthe conversionof 2-alkyl-l -ethynylbenzenes to indenes was disclosed by the group of Liu [41]. Their proposed mechanism involves the stepwise insertion of a ruthenium vinylidene into a benzylic C— H bond (Scheme 9.21). 

XXVII Inden BFj-Atherat + optiscli aktive Co-katalysatorcn (1-a-Methyl-benzyl-alkohol, Tosyl-L-Valin, Campher) in n-Hexan odcr CHClj bei 0° bzw. -SO C disyndiotaktisch (84,104)... 

The first such reaction to be described in the literature was the substitution at the benzylic C—H bonds of indene, which occurs upon irradiation of indene and acrylonitrile [85], This reaction involves electron transfer followed by proton transfer and radical coupling ... 

Indenes lacking benzylic hydrogens (e.g., 1,1-dimethylindene) give no substitution products upon irradiation with acrylonitrile. 

Benzyl cations generated from benzyl alcohols or quinone methides by the action of S11CI4 undergo [3-(-31-cycloaddition of allylsilanes leading to tetrahydronaphthalenes.1 With secondary and tertiary benzyl cations, a competing [3 + 2]-pathway forms dihydro(177)indenes. 

First, aluminum chloride abstracts the reactive benzylic fluorine from 1-phenylperfluoropropene and leaves a positively charged species that cyclizes to an indene derivative. The reactive benzylic fluorine atoms in this intermediate are replaced by chlorine [55] in a way similar to the replacement of fluorine by halogens in Explanations 22,23, and 24. 

Indanyl)-phenol 16 was obtained by reacting p-methoxy-phenyl-acetic acid ethyl ester with benzylchloride to form a-benzyl-p-methoxyphenyl ethyl acetate, saponification into the acid, conversion of the acid with thionylchloride into the chloride, cyclization to 2-p-methoxy-phenyl-l-indanone, NaBH4 reduction to 2-p-methoxyphenyl-l-indanole, dehydration with p-toluene-sulphonic acid in toluene to 2-p-methoxyphenyl-indene, catalytic hydrogenation to 2-p-methoxyphenyl-indene, and treating the ether with HBr [Eq. (5)]. 

Indene gives [97] and [98]. The benzylic radical [99] is probably reduced by the dicyanobenzene radical anion to give its anion which is protonated by the methanol to give [97]. In these reactions phenanthrene is acting purely as a sensitiser. Phenanthrene has been found (Yamada et al., 1977) to react with... 

Based on the benzyl derivative (26), the first stable carborane-containing simple enol (27) was synthesized2 (Scheme 8). The acid chloride (28) readily enters into a Friedel-Crafts reaction with mesitylene to give ketone (29). Under the action of BuLi on a benzene-ether solution of ketone (29) enolate (30) is formed. Treatment of the latter with diluted HC1 solution results in enol (27). Starting from the benzyl derivative (31), carboranyl-substituted indene (32) was synthesized by intramolecular cyclization with a formation of ketone (33), whose reduction (34) followed by dehydration results in (32) (Scheme 9). 

The tertiary benzyl cation (7), which would be preferentially formed by hydride abstractions in addition to rearrangement of (6), may be a precursor for chain unsaturation and for the formation of indenes. 

Conversions of 3-arylcyclopropenes into indenes using Ag(I) and Pd(0) have been reported " . The silver-catalysed opening of the three-membered ring in cyclopro-pabenzene proceeds via a benzylic carbocation. 

Compounds containing active hydrogen atoms (pK = 11-25) could be brominated when DBU was added dropwise into a mixture of substrate (phenylacetylene, diethyl butylmalonate, indene, or fluorene) and BrCClj in benzene (78CL73). Compounds with lower acidity (pK 29) exhibited no reaction. With more acidic derivatives (diethyl malonate and benzyl cyanide), oxidative dimerization also occurred. Oxidative dimerization also took place when BrCClj was added dropwise into a solution of active methylene compound and DBU in benzene. The ratio of the reaction products depended on the ratio of DBU and BrCCIj. 

In addition to phenylacetonitrile and fluorene, various active methylene compounds such as indene, propiophenone, phenyl propionate, benzyl phenylacetate afforded the corresponding carboxylated products by the carboxylation reaction with La(0 Pr)3-Ph-N=C=0-C02 system. Of fundamental and practical importance is that S-benzyl thiopropionate was effectively carboxylated into a thioester of 2-methylmalonate in a good yield, since this reaction is related to the biological carboxylation of propionyl coenzyme A with a biotin enzyme. Other thioesters were also carboxylated similarly, where successful examples were thioesters of phenylacetic, acetic, and isovaleric acids carrying active methylene and methyne groups, respectively. 

Methyl-phenyl- 3099 C, H,Br Cyclopropane l-(a-Bromo-benzyl)- 1445 Indene... 

With secondary and tertiary benzyl cations a competing [3-1-2] pafhway leads to fhe formation of dihydro(lH)indenes. 

These may seem strange molecules to have a place in the new chiral pool but they were made on a vast scale by Merck in the synthesis of their HIV protease inhibitor crixivan (Indinavir). They both come from Jacobsen epoxidation of indene 283 (chapter 25) the anti-compound 285 by opening the epoxide 284 at the benzylic centre with azide ion.51... 

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