Indoline derivatives, generation

The major isomer 34 is desilylated with TBAF, and oxidative cleavage of the diol with sodium periodate generates the corresponding aldehyde 35, the racemic form of which is a known intermediate in the total synthesis of racemic CP compounds. The conversion to the indoline derivative mt-31 therefore follows the strategy of the racemic route. Circular dichroism (CD) spectroscopy verified the identity of the synthetic mt-31 as the enantiomer of the naturally derived indoline (—)-31. Synthetic ent-31 was also processed to give ent-1 and ent-2. 

Julia et al. have employed intramolecular reactions of arynes generated from indoline derivatives for closure of a six-membered ring linking the 3-and 4-positions. Thus, 103 is obtained from 102 by treatment with sodium... 

Finally, Carter et al. have applied a similar protocol to prepare a series of chiral pyrrolidine, piperidine and indoline derivatives. Indeed, these products were generated from the corresponding enals through intramolecular aza-... 

The unexpected formation of cyclopenta[b]indole 3-339 and cyclohepta[b]indole derivatives has been observed by Bennasar and coworkers when a mixture of 2-in-dolylselenoester 3-333 and different alkene acceptors (e. g., 3-335) was subjected to nonreductive radical conditions (hexabutylditin, benzene, irradiation or TTMSS, AIBN) [132]. The process can be explained by considering the initial formation of acyl radical 3-334, which carries out an intermolecular radical addition onto the alkene 3-335, generating intermediate 3-336 (Scheme 3.81). Subsequent 5-erafo-trig cyclization leads to the formation of indoline radical 3-337, which finally is oxidized via an unknown mechanism (the involvement of AIBN with 3-338 as intermediate is proposed) to give the indole derivative 3-339. 

A spiro indoline (347) has been isolated from the reaction of the quaternized derivative of 5-methoxy-l-methyl-3-(2-dimethylaminoethyl)indole with lithium in liquid ammonia in the absence of a proton donor (68TL81). The product presumably arises from the rapid sequential addition of two electrons to generate the dianion of the tryptamine, which facilitates the nucleophilic displacement of trimethylamine. Reduction in the presence of methanol produces the 4,7-dihydrotryptamine (see Section 3.05.1.5). 

Jouannetaud and co-workers229 have explored electrophilic trifluoromethylation under superacidic conditions of aniline derivatives229 and /V-heterocycles. Methyl-substituted anilines and substituted acetanilides [Eq. (5.85)] react with the CC13+ cation generated from CC14 in HF-SbF5 followed by fluorination to yield the corresponding trifluoromethyl derivatives. Under similar conditions, indolines are transformed to the 6-triluoromethyl derivatives, whereas substituted indoles yield 5-triluoromethyl derivatives.230... 

Other means for generation and annulation of aryl radicals involve treatment of A -(t>-bromophenyl)propylamides with BusSnH/AIBN, which gives 3-alkylideneoxindoles <2(X)0J(P1)763>, or exposure of A -allyl(t>-iodoanilines) to fluorous tin hydride reagents, affording indolines <1999JA6607>. A set of indolines, for instance 239, have been obtained by radical cyclization of precursors such as 240, which were derived from A -allylanilines (Equation 76) <1999TL2533>. 

A number of oxynitroxide radicals that, although not ionic, are structurally similar to the nitroanions were obtained by adding in situ-generated triphenyl-germyl radicals to several nitro derivatives attention has been addressed to nitrospiro[indoline-naphthopyrans] 63, 66, and 67, and the resulting adducts have been attributed structures 70-72.59... 

Benzyne generation. As a fluoride source for initiating the generation of benz3fue from 2-trimethylsilylphenyl Inflate, the effectiveness of Bu4N(Ph3SiF2) is obvious. New possibilities for cycloaddition with enamides leading to indolines and isoquinohne derivatives have been explored. ... 

The aryllithiums derived from iV,iV-diallylarylamines with an ortho halogen by exchange with an alkyllithium cyclise by addition to an allyl group double bond generating a primary alkyllithium which can be trapped with electrophiles finally producing indolines. ... 

Free radicals can also be generated by the photolysis of thiohydroxamate systems derived from thiazolones and thiopyridones. Photolysis of the thiazolone derivative (236) yields the pyrrolo[l,2-ajindole (238), together with a trace of the related indoline and some dimeric product (239). Reaction of the pyridone thiohydroxamate (237) gives a dimer as the major product (Scheme 72) <93JOC2768>. 

Cross-coupling carboamination reactions between allenes and 2-haloaniline derivatives or halogenated allylic amines have also been employed for the generation of substituted indolines, and use of an appropriate chiral catalyst for these transformations leads to formation of enantioenriched products [52]. For example, Larock has described the synthesis of indoline 56 via the Pd-catalyzed reaction of aryl iodide 54... 

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