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Мызников, Л. В.; Artamonova, T. V.; Bel'skii, V. K.; Сташ, А. И.; Skvortsov, N. K.; Koldobskii, G. I.

doi:10.1023/a:1021672317335

Cited by 16 publications

(14 citation statements)

References 22 publications

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“…[107] Tritylation of a 5-ST or of unsubstituted tetrazole should probably proceed through the S N 1 mechanism. However, in the case of unsubstituted tetrazole this reaction still displayed a high regioselectivity even without steric control of the process.…”

Section: Alkylation Of 5-stsmentioning

confidence: 99%

Synthesis and Functionalization of 5‐Substituted Tetrazoles

2012

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Tetrazoles are synthetic heterocycles with numerous applications in organic chemistry, coordination chemistry, the photographic industry, explosives, and, in particular, medicinal chemistry. In organic chemistry, 5‐substituted tetrazoles are used as advantageous intermediates in the synthesis of other heterocycles and as activators in oligonucleotide synthesis. In drug design, 5‐monosubstituted tetrazoles are the most important tetrazole derivatives because they represent non‐classical bioisosteres of carboxylic acids, with similar acidities but higher lipophilicities and metabolic resistance. In this review we focus on the preparation and further functionalization of these heterocycles. Firstly, the role of 5‐substituted tetrazoles in medicinal chemistry is described, including examples of their effects on pharmacokinetics, pharmacodynamics, and metabolism of the associated drugs. Then, the main synthetic approaches to 5‐substituted tetrazoles – consisting of methods based on acidic media/proton catalysis, Lewis acids, and organometallic or organosilicon azides – are presented, from the early procedures to the most recent ones, with special attention paid to the reaction mechanisms. Functionalization of 5‐substituted tetrazoles is a challenging task because it usually leads to the formation of two isomers, 1,5‐ and 2,5‐disubstituted tetrazoles, in various ratios. In this overview, reactions with high or unusual regioselectivities are described, with comments on the possible mechanisms. Microwave‐assisted approaches to the synthesis and functionalization of 5‐substituted tetrazoles are also included.

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Section: Alkylation Of 5-stsmentioning

confidence: 99%

Synthesis and Functionalization of 5‐Substituted Tetrazoles

2012

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“…This intermediate, however, can only explain the experimental outcome if 4 d , e selectively prefers “cleavage b” to afford 5 d , e , because products of type 3 , which would result from “cleavage a”, are not found in the thermolysis of 19 d , e . In the literature,23 a reaction mechanism with dipole 20 and a longer alternative sequence was suggested, but the corresponding steps are less plausible.…”

Section: Resultsmentioning

confidence: 99%

“…For comparison, we prepared the new heptafulvenes 5d and 5e by using aw ell-known [23] method( Scheme 4). Thermolysis of the 2 H-tetrazole 19 d,w hich is easily accessible by tritylation of the sodium tetrazolate 18 d, [24] furnished the desired product 5d.T his compound was identical with the 5d obtained from 15 d and trisyl azide.…”

Section: Resultsmentioning

confidence: 99%

“…We assume that the transformation 19!5 is startedb yl iberation of dinitrogen and generation of the dipole 20,w hich can also be described as carbene 20'.I ntramolecular cheletropic addition of this short-lived intermediate gives the norcaradiene 21,w hich undergoes electrocyclic ring openingt op roduce cycloheptatriene 22 followed by [8+ +2] cycloreversion that leads to 5 and dinitrogen.I np rinciple, cleavage of 21 with loss of an itrogenm olecule and formation of the bicyclobutane 4d,e is also possible. This intermediate, however,c an only explain the experimental outcome if 4d,e selectively prefers "cleavage b" to afford 5d,e,b ecause products of type 3,w hich would result from "cleavage a", are not found in the thermolysis of 19 d,e.I nt he literature, [23] ar eaction mechanism with dipole 20 and al onger alternative sequence was suggested, but the corresponding steps are less plausible.…”

Section: Resultsmentioning

confidence: 99%

“…In analogy with a known protocol,23 sodium 5‐cyanotetrazolate sesquihydrate24 ( 18 d ; 360 mg, 2.5 mmol) in water (10 mL) was added to tetrabutylammonium bromide (64.5 mg, 0.2 mmol) in chloroform (10 mL). A solution of triphenylmethyl chloride (0.84 g, 3 mmol) in chloroform (20 mL) was added, and the mixture was stirred overnight at room temperature.…”

Section: Methodsmentioning

confidence: 99%

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Rearrangement Reactions of Tritylcarbenes: Surprising Ring Expansion and Computational Investigation

Banert

Hagedorn

Pester

et al. 2015

Chemistry A European J

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As a rule, acetylides and sulfonyl azides do not undergo electrophilic azide transfer because 1,2,3-triazoles are usually formed. We show now that treatment of tritylethyne with butyllithium followed by exposure to 2,4,6-triisopropylbenzenesulfonyl azide leads to products that are easily explained through the generation of short-lived tritylethynyl azide and its secondary product cyanotritylcarbene. Furthermore, it is demonstrated that tritylcarbenes generally do not produce triphenylethenes exclusively, as was stated in the literature. Instead, these carbenes always yielded also (diphenylmethylidene)cycloheptatrienes (heptafulvenes) as side products. This result is supported by static DFT, coupled cluster, and ab initio molecular dynamics calculations. From these investigations, the fused bicyclobutane intermediate was found to be essential for heptafulvene formation. Although the bicyclobutane is also capable of rearranging to the triphenylethene product, only the heptafulvene pathway is reasonable from the energetics. The ethene is formed straight from cyanotritylcarbene.

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Tetrazoles. Part 44. Synthesis and Chemical Properties of 5‐Substituted 2‐Triphenylmethyltetrazoles.

et al. 2003

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Tetrazole derivativesTetrazole derivatives R 0310 Tetrazoles. Part 44. Synthesis and Chemical Properties of 5-Substituted 2-Triphenylmethyltetrazoles. -Tritylation of 5-substituted tetrazoles (I) under phase--transfer catalysis conditions provides regioselectively the corresponding 2-trityltetrazoles (III), which can be used to protect N-heterocycles [→(V)] and primary alcohols [→(VII)]. Thermolysis of 2-trityltetrazoles in benzonitrile gives 3,6-disubstituted tetrazines (VIII), while thermolysis in dodecane affords difficultly accessible 8,8-diphenylheptafulvenes (IX). The structure of the latter compound is proven by X-ray analysis. -(MYZNIKOV, L. V.; ARTAMONOVA, T. V.; BEL'SKII, V. K.; STASH, A. I.; SKVORTSOV, N. K.; KOLDOBSKII, G. I.; Russ.

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Untitled

Cited by 16 publications

References 22 publications

Synthesis and Functionalization of 5‐Substituted Tetrazoles

Synthesis and Functionalization of 5‐Substituted Tetrazoles

Rearrangement Reactions of Tritylcarbenes: Surprising Ring Expansion and Computational Investigation

Tetrazoles. Part 44. Synthesis and Chemical Properties of 5‐Substituted 2‐Triphenylmethyltetrazoles.

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