1,4-Disubstituted and 1,4,5-Trisubstituted 2-[(Benzotriazol-1-yl)methyl]pyrroles as Versatile Synthetic Intermediates

The CH(2)Bt substituent, unlike previously used CH(2)X substituents, enables (i) the synthetic elaboration of pyrroles with unsubstituted ring positions and (ii) electrophilic as well as nucleophilic substitutions to give pyrroles of type pyrrolyl-2-CHENu. Thus, 1,4-disubstituted (7) and 1,4,5-trisubstituted 2-[(benzotriazol-1-yl)methyl]pyrroles (15) were easily prepared from the reaction of 5-(benzotriazol-1-yl)-1,2-epoxy-3-pentynes 4 or 14 with primary amines in i-PrOH. The 2-(benzotriazol-1-yl)methyl side chains of compounds 7 and 15 were elaborated by nucleophilic substitution and also by initial alkylation followed by replacement or elimination of the benzotriazolyl moiety to afford a variety of 1,2,4-trisubstituted (6, 8-9, 11-13) and 1,2,4,5-tetrasubstituted pyrroles (18, 20-22).     

Efficient Syntheses of Substituted Carbazoles and Cyclopent[b]indoles from 1-Methyl-3-(benzotriazol-1-ylmethyl)indole

1-Methyl-3-(benzotriazol-1-ylmethyl)indole (1) undergoes lithiation and 1,4-addition with a variety of alpha,beta-unsaturated ketones and aldehydes. Subsequent treatment with an acidic resin in refluxing 1,4-dioxane causes intramolecular cyclization followed by aromatization to furnish a wide range of 1,3-di-, 2,3-di-, and 1,2,3-trisubstituted carbazoles 6a-j and 8 in moderate to excellent yields. NMR study is described to discriminate between structures of types 6 and 8 on the basis of (1)H-(13)C long-range correlation. Treatment of 1 with styrenes in the presence of zinc bromide results in formal [3 + 2] cycloaddition to give cyclopent[b]indoles 14a-c in good yields. When 1 is first lithiated and reacts with electrophiles, the resulting alkylation products undergo similar [3 + 2] additions with styrenes to give 1-functionalized cyclopent[b]indoles 15 and 16with a high degree of stereoselectivity.     

Convenient Synthesis of Julolidines Using Benzotriazole Methodology

Reaction of N,N-bis[(benzotriazol-1-yl)methyl]aniline (2) with 1-vinylpyrrolidin-2-one gives a mixture of diastereomeric 1,7-bis(2-oxopyrrolidin-1-yl)julolidines 3. After reduction of 3 with LAH, the predominant trans diastereomer of 1,7-di(pyrrolidin-1-yl)julolidine (4) is separated. Reaction of 2 with ethyl vinyl ether yields predominantly trans-1,7-di(benzotriazol-1-yl)julolidine (11). Stepwise synthesis from tetrahydroquinoline 15 gives access to julolidines with two different substituents on C-1 and C-7. Reaction of 1-[(benzotriazol-1-yl)methyl]-1,2,3,4-tetrahydroquinoline (25) with enolizable aldehydes gives a mixture of tetrahydroquinolines 26-29 which are converted into single julolidine products upon treatment with sodium hydride, LAH, or phenylmagnesium bromide. Reactions of 1,2,3,4-tetrahydroquinolines with benzotriazole and 2 molar equiv of enolizable aldehydes gives 1,2,3-trisubstituted julolidines 38-41, which with lithium aluminum hydride, sodium hydride, or a Grignard reagent produce single diastereomers of products 42, 43, and 45, respectively.     

Benzotriazol-1-ylmethylammonium salts synthesis and reactivity

Benzotriazol-1-ylmethylamines on treatment with alkylating agents afford benzotriazol-1-ylmethylammoni-um salts, also available from reactions of chloromethylbenzotriazole with tertiary amines. In deuterated solvents under basic conditions the methylene protons of these salts exchange with deuterium. At elevated temperatures, an alkyl group substituent migrated from the ammonium center to the benzotriazolyl N-3. Reactions of the salts with Grignard reagents afforded various products arising from substitution of the ammonium moiety and/or from attack on the benzotriazolyl N-3 or on the benzenoid ring.     

Unusual deoxygenation and reactivity studies related to O6-(benzotriazol-1-yl)inosine derivatives

New and unusual developments related to the chemistry of O6-(benzotriazol-1-yl)inosine derivatives are reported. First, a simple, scalable method for their syntheses via the use of PPh3/I2/HOBt has been developed and has been mechanistically investigated by 31P(1H) NMR. Studies were then conducted into a unique oxygen transfer reaction between O6-(benzotriazol-1-yl)inosine nucleosides and bis(pinacolato)diboron (pinB-Bpin) leading to the formation of C-6 (benzotriazol-1-yl)purine nucleoside derivatives and pinB-O-Bpin. This reaction has been investigated by 11B(1H) NMR and compared to pinB-O-Bpin obtained by oxidation of pinB-Bpin. The structures of the C-6 (benzotriazol-1-yl)purine nucleosides have been unequivocally established via Pd-mediated C-N bond formation between bromo purine nucleosides and 1H-benzotriazole. Finally, short and extremely simple synthesis of 1,N6-ethano- and 1,N6-propano-2'-deoxyadenosine are reported in order to demonstrate the synthetic versatility of the O6-(benzotriazol-1-yl)inosine nucleoside derivatives for the assembly of relatively complex compounds.     

O6-(benzotriazol-1-yl)inosine derivatives: easily synthesized, reactive nucleosides

A novel class of O6-(benzotriazol-1-yl)inosine as well as the corresponding 2'-deoxy derivatives can be conveniently prepared by a reaction between sugar-protected or -unprotected inosine or 2'-deoxyinosine nucleosides and 1H-benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP). The reaction appears to proceed via a nucleoside phosphonium salt, and in the absence of any additional nucleophile, the released 1-hydroxybenzotriazole undergoes reaction with the formed phosphonium salt leading to the requisite O6-(benzotriazol-1-yl)inosine or 2'-deoxyinosine derivatives. Isolation and characterization of the phosphonium salt as well as analysis by 31P{1H} NMR appear to be consistent with this reaction pathway. The resulting O6-(benzotriazol-1-yl)inosine derivatives are effective as electrophilic nucleosides, undergoing facile reactions with a variety of nucleophiles such as alcohols, phenols, amines, and a thiol. Unusual and challenging nucleoside derivatives such as an aryl-bridged dimer, a nucleoside-amino acid conjugate, and a nucleoside-nucleoside dimer have also been synthesized from the O6-(benzotriazol-1-yl)-2'-deoxyinosine derivative. Finally, a fully protected DNA building block, the O6-(benzotriazol-1-yl)-2'-deoxyinosine 5'-O-DMT 3'-O-phosphoramidite, has been prepared and a preliminary evaluation of its use for DNA modification has been performed. Results from these studies indicate several important facts: A single, simple methodological approach provides a class of stable, isolable ribo and 2'-deoxyribonucleoside derivatives that possess excellent reactivity for SNAr chemistry with a wide range of nucleophiles. Also, a benzotriazolyl nucleoside phosphoramidite appears to be a suitable reagent for incorporation into DNA for purposes of site-specific DNA modification.     

Synthesis of N-cycloalkenylazoles

N-(1-Cycloalkenyl)pyrroles 3a,b, -pyrazoles 6a,b, and -imidazoles 9a,b were synthesized via elimination of benzotriazole or 5-phenyltetrazole from the corresponding 1-[1-(heterocycyl)cycloalkyl]benzotriazoles 2, 5, and 8 or 1-[1-(heterocycyl)cyclohexyl]-5-phenyltetrazole (12 and 14). Intermediates 2, 5, 8, 12 and 14 were obtained by cyclizations of dihaloalkanes with N-(benzotriazol-1-ylmethyl)heterocycles, 1-imidazol-1-ylmethyl-5-phenyltetrazole (11), or 1-pyrazol-1-ylmethyl-5-phenyltetrazole (13) in the presence of n-BuLi.     

Versatile solid-phase synthesis of s-arylisothioureas

Resin-bound amines 4a-m condense with di(benzotriazol-1-yl)methanimine 6 to give 1H-benzotriazole-1-carboximidamide resins 7a-m, which subsequently react with thiols 9a'-g' followed by cleavage affording nonprotected isothioureas 1aa'-mg' in high yields and with good purities. Analogous reactions with secondary amines activated with EtMgBr lead to guanidines 2a,b,e-g in moderate yields. Resin-bound isothioureas 1 are converted by acyl chlorides or carboxylic acids into acyl derivatives 12a-n in high yields and with good purities.     

Solid-phase synthesis of 1,2,5-trisubstituted 4-imidazolidinones

An efficient method for the preparation of 1,2,5-trisubstituted 4-imidazolidinones is presented. The synthetic approach is based on the formation of an N-[1-(benzotriazol-1-yl)alkyl] moiety on the amino group of a MBHA resin-bound amino acid. The nucleophilic substitution of the benzotriazole group with an amidic nitrogen results in the formation of a five-membered imidazolidinone ring. The reaction is nonstereospecific and produces diastereomers in ratios that vary depending on the substituents on the ring. A variety of N-alpha-alkylated amino acids were cyclized with aromatic, aliphatic, and heterocyclic aldehydes to determine optimal reaction conditions and to select building blocks for the future preparation of a large, diverse range of individual trisubstituted imidazolidinones as well as a mixture-based combinatorial library.     

A Short and Efficient Synthesis of Novel N-(2,3-dihydro-2-oxo-5-phenyl-1 H -1,4-benzodiazepin-3-yl)-2-carboxamides

 Several novel N-(2,3-dihydro-2-oxo-5-phenyl-1H-1,4-benzodiazepin-3-yl)-2-carboxamides were prepared by acyl coupling of 2-aminobenzophenones with α-(benzotriazol-1-yl)-N-acylglycines followed by displacement of the benzotriazole ring with ammonia and cyclization of the resulting monoacyl aminals. In addition to high yields and shorter reaction sequences due to avoiding deprotection and acylation of the protected 3-amino-1,4-benzodiazepin-2-one intermediates, the present approach did not involve the use of toxic and odoriferous materials as is the case with other methods.     

6-Substituted 2-(2-benzothiazolyl) [1, 2, 3] benzotriazol-1-oxides and the kinetics of their formation

6-Substituted 2-(2-benzothiazolyl) [1, 2, 3] benzotriazol-1-oxides were prepared by a base catalyzed cyclization reaction of 2-(4-substituted 2-nitrophenylhydrazino) benzothiazoles. Influence of substitution in position 4 on the cyclization reaction rate was followed and correlated with Hammett constants.     

A Short and Efficient Synthesis of Novel N-(2,3-dihydro-2-oxo-5-phenyl-1H-1,4-benzodiazepin-3-yl)-2-carboxamides

Summary.  Several novel N-(2,3-dihydro-2-oxo-5-phenyl-1H-1,4-benzodiazepin-3-yl)-2-carboxamides were prepared by acyl coupling of 2-aminobenzophenones with α-(benzotriazol-1-yl)-N-acylglycines followed by displacement of the benzotriazole ring with ammonia and cyclization of the resulting monoacyl aminals. In addition to high yields and shorter reaction sequences due to avoiding deprotection and acylation of the protected 3-amino-1,4-benzodiazepin-2-one intermediates, the present approach did not involve the use of toxic and odoriferous materials as is the case with other methods. Received September 20, 2000. Accepted (revised) November 29, 2000     

Syntheses and transformations of substituted benzazolyl- and tetrazolyl(benzotriazol-1-yl)methanes

Condensation reactions of o-hydroxy- and o-mercaptoanilines, and o-phenylenediamine with (benzotriazol-1-yl)acetic acid result in (1,3-benzazol-2-yl)(benzotriazol-1-yl)methanes. Cycloaddition of sodium azide to (benzotriazol-1-yl)acetonitrile leads to (1,2,3,4-tetrazol-5-yl)(benzotriazol-1-yl)methane. The diazolo-substituted benzotriazolylmethanes thus obtained were mono- and di-alkylated at the methylene group and the displacement of the benzotriazole group by nucleophiles was investigated.     

Synthesis of novel hydropyrazolopyridine derivatives in solvent-free conditions via benzotriazole methodology

The reaction between 5-[N-(benzotriazol-1-ylmethyl)amino]-3-tert-butyl-1-phenylpyrazole or 5-amino-4-(benzotriazol-1-ylmethyl)-3-tert-butyl-1-phenylpyrazole with some unactivated and electron-rich alkenes has followed heterocyclization reactions to yield hydropyrazolopyridines, under solvent-free conditions, as predicted by benzotriazole methodology in contrast with those results obtained under solution. The reaction mechanism was proposed after fully spectroscopic analysis of final products and intermediates.     

Synthesis of 1-(benzotriazol-1-yl)alkyldiphenylphosphine oxides and their transformations to novel benzotriazol-1-yl-substituted cyclopropanes

Diphenylphosphinous anion reacted with chloromethylbenzotriazole to give (benzotriazol-1-yl)methyldiphenylphosphine oxide, which, after lithiation, was alkylated to give 1-(benzotriazol-1-yl)alkyldiphenylphosphine oxides in good yield. Treatment of 1-(benzotriazol-1-yl)alkyldiphenylphosphine oxides with n-butyllithium followed by condensation with epoxides, afforded benzotriazol-1-yl-substituted cyclopropanes, which underwent further lithiation and subsequent reaction with numerous electrophiles to provide a variety of novel benzotriazol-1-yl-substituted cyclopropane derivatives.     

Novel routes to 1-aryl-1,4-dihydro-3(2H)-isoquinolinones and 2-substituted or 2,3-disubstituted benzofurans by intramolecular cyclizations

N-(α-Benzotriazolylalkyl)arylacetamides, readily available from an arylacetamide, an aldehyde and benzotriazole, undergo intramolecular cyclization under acidic conditions to give 1-aryl-1,4-dihydro-3(2H)-isoquinolinones in good to excellent yields. Similarly, 2-(benzotriazol-1-yl)-2-(o-hydroxyphenyl)ethanols, obtained by lithiation of 2-(benzotriazol-1-ylmethyl)phenols followed by quenching with aldehydes or ketones, eliminate a molecule of water and a molecule of benzotriazole yielding 2-substituted and 2,3-disubstituted benzofurans.     

A strategy for the synthesis of 2-aryl-3-dimethylaminopyrazolo-[3,4-c]pyridines that utilizes [4+1] cycloaddition reactions of 5-arylazo-2,3,6-trisubstituted pyridines

In order to explore the viability and generality of a recently uncovered [4+1] cycloaddition based strategy for the preparation of pyrazolo[3,4-c]pyridine derivatives, members of a series of 5-arylazo-2,3,6-trisubstituted pyridines were prepared by reactions of 3-oxo-2-arylhydrazonopropanals with 3-oxo-3-phenylpropionitrile. The results show that 3-oxo-3-phenylpropionitrile reacts with hydrazone substrates, which do not contain electron-withdrawing substituents on the N-aryl ring of the arylhydrazone moieties, to efficiently produce 6-aryl-2-phenyl-5-arylazonicotinonitriles. In contrast, 2-amino-6-aryl-5-arylazo-3-benzoylpyridines are generated in reactions of 3-oxo-2-arylhydrazonopropanals, which contain electron-withdrawing substituents on the N-aryl moiety. In the forecasted manner, the 6-aryl-2-phenyl-5-arylazonicotinonitriles undergo smooth reactions with dimethylformamide dimethylacetal (DMF-DMA) that led to formation of a new class of 2-aryl-3-dimethylaminopyrazolo[3,4-c]pyridines. The mechanism for this process involves a [4+1] cycloaddition reaction that takes place through initial nucleophilic addition of dimethylamino)methoxycarbene, generated from DMF-DMA, to the azadiene moiety of the arylazopyridines followed by cyclization of the formed zwitterionic intermediate.     

Meerwein芳基化反应(Ⅰ)——N-乙烯基邻苯二甲酰亚胺的芳基化

Meerwein芳基化反应是在烯键上导入芳基的一种重要方法:ArN₂Cl+RCH=CHZ→ArCR=CHZ+ArCHRCHClZ化合物RCH=CHZ中Z为电子取代基时,反应容易进行,Z为OAc、OR时,也可以起芳基化反应,但烯胺(Z=NR₂)与芳基重氮盐作用,只得到偶联产物。烯胺与N,N-二烷基苯胺为插烯物(Vinglogs),由于氮原子上的未共电子对与π键共轭,使烯键或苯环碳原子上电子密度增加,容易起偶联反应。     

Efficient approaches toward the solid-phase synthesis of new heterocyclic azoniaspiro ring systems: synthesis of tri- and tetrasubstituted 10-oxo- 3,9-diaza-6-azoniaspiro[5.5]undecanes

[Reaction: see text]. An efficient approach for the parallel solid-phase synthesis of novel heterocyclic azoniaspiro ring systems is described. The target compounds, the 1,8,9-trisubstituted 10-oxo-3,9-diaza-6-azoniaspiro[5.5]undecanes, were obtained starting from resin-bound reduced dipeptides. The azoniaspiro cation was formed by intramolecular attack of a tertiary nitrogen on pendent alpha-bromocarbonyl. N-3 acylated and N-3 alkylamino carbonyl derivatives of the 1,8,9-trisubstituted 10-oxo-3,9-diaza-6-azoniaspiro[5.5]undecanes were obtained following in solution treatment of the N-3 azoniaspiro derivatives with different carboxylic acids and isocyanates.     

A novel rearrangement to 1,2,4-triazolo[1,5-a]quinoxalines

Reactions of benzyl bromide or benzyl cinnamate with N-(benzotriazol-1-ylmethyl)arylimidoyl chlorides (2a,b) in the presence of t-BuOK occur with opening of the benzotriazole ring affording 1,2,4-triazolo[1,5-a]quinoxalines (3a,b). A possible reaction mechanism is discussed.