Intramolecular Cycloadditions of Photogenerated Azaxylylenes with Oxadiazoles Provide Direct Access to Versatile Polyheterocyclic Ketopiperazines Containing a Spiro-oxirane Moiety

Kumar, N. N. Bhuvan; Kuznetsov, Dmitry M.; Kutateladze, Andrei G.

doi:10.1021/ol5033909

Cited by 28 publications

(12 citation statements)

References 19 publications

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“…This type of ESPT cycloaddition reaction was also successful in the formation of epoxy and spiro‐oxirane products but with limited enantio or diastereoselectivity.…”

Section: Chemical Transformationsmentioning

confidence: 99%

Chirality and Excited State Proton Transfer: From Sensing to Asymmetric Synthesis

Posey

Hanson

2019

ChemPhotoChem

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proton transfer (ESPT) is a unique photochemical process where the electron density shift of a molecule in the excited state dramatically decreases the pK a value of a proton donor site. A majority of ESPT research to date has focused on achiral molecules but there is growing interest in understanding/harnessing ESPT to/from chiral molecules. This review summarizes and critically examines the literature to date describing the role of ESPT in enantioselective fluorescence sensing, asymmetric synthetic organic chemistry, and photoisomerization of chiral molecules. Our goal is to show that despite ESPT of chiral molecules being a relatively new pursuit, there has been significant progress and even greater potential for ESPT in these and other applications yet to be realized.[a] V.

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“…This type of ESPT cycloaddition reaction was also successful in the formation of epoxy and spiro‐oxirane products but with limited enantio or diastereoselectivity.…”

Section: Chemical Transformationsmentioning

confidence: 99%

Chirality and Excited State Proton Transfer: From Sensing to Asymmetric Synthesis

Posey

Hanson

2019

ChemPhotoChem

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“…9 Generally, in synthetic procedures established for the dehydrative cyclisation of semicarbazides, hydrazides are frequently used and corrosive reagents such as concentrated sulfuric acid or POCl 3 , boron triuoride diethyl etherate or Burgess reagent, phosphorus oxychloride, polyphosphoric acid, thionyl chlorides are involved, where these reagents result in inexible byproducts in the reaction and inadequate yields, and have no experimental diversity. [10][11][12][13][14] To avoid undesirable reagents in the reaction, presently we have focused our deep interest on the improvement of novel synthetic strategies to obtain attractive functionalized oxadiazoles. In our determination to chemically link these biologically important heterocyclic molecules, we wanted to develop a modern synthetic route for the preparation of 5-substituted-3H- [1,3,4]-oxadiazol-2-one derivatives as major chemical skeletons.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, synthetic procedures established on dehydrative cyclisation of semicarbazides, hydrazides are frequently used and curiously involved a corrosive reagents such as concentrated sulfuric acid or POCl 3 , boron trifluoride diethyl etherate or Burgess reagent, phosphorus oxychloride, polyphosphoric acid, Thionyl chlorides where these conversely, results in an inflexible byproduct in the reaction and where the examinations were inadequate and has no experimental diversity [10][11][12][13][14] . To avoid undesirable reagents in the reaction, presently we have been focused our deep interest in the improvement in novel synthetic strategies to obtain attractive functionalized oxadiazoles.…”

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confidence: 99%

Synthesis of 5-substituted-3H-[1,3,4]-oxadiazol-2-one derivatives: a carbon dioxide route (CDR)

2015

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A carbon dioxide route (CDR) of making biologically important 5-substituted-3H-[1,3,4]oxadizole-2-one (SHOs) has been accomplished through synthesis and cyclization of varieties of hydrazides as their key intermediates. All these hydrazides were prepared readily in 95~98% by reacting acid chlorides with hydrazine monohydrate in the initial step. Then, SHOs were obtained in high yields from hydrazides by reacting them with carbon dioxide under basic conditions. More notable than high yields, the present CDR process for the first time has succeeded in straightforward cyclization reaction leading to SHOs formation with the simple reagents in ethanol solution.

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“…Kutateladze has reported an intramolecular cycloaddition of photogenerated azaxylylenes with oxadiazoles to give ketopiperazines (Scheme 60). 59 Upon irradiation with a UV lamp (300-400 nm), a photoassisted tautomerization to the azaxylylene occurred. Intramolecular [4+4] cycloaddition to the oxadiazole moiety and loss of N 2 gave the desired ketopiperazine.…”

Section: Scheme 59 Mechanism Of Photochemical [4+2] Cycloaddition To mentioning

confidence: 99%

Photochemical Synthesis of Azaheterocycles

Tanoury

2016

Synthesis

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Synthetic organic photochemistry is a field that continues to offer unique routes to organic structures not typically accessed from thermal reactions. In this review, the photochemical synthesis of five-, six-, seven-, and eight-membered-ring azaheterocycles, as well as some aza-macrocycles, is discussed. The discussion will focus on methods where heterocycle formation occurs during or as a result of a photochemical event. Reaction mechanisms will be discussed also, as these provide a rationale for understanding the synthetic results. 1 Introduction 2 Five-Membered Rings 2.1 Cyclization Reactions 2.2 Cycloadditions 2.3 From Aromatic and Vinyl Azides 2.4 earrangements 2.5 Other Individual Methods 3 Six-Membered Rings 3.1 Cyclization Reactions 3.2 Isocyanide Insertions 3.3 Cycloadditions 4 Seven-Membered Rings and Larger 5 Conclusion Key words azaheterocycles, photocycloaddition, photocyclization, photorearrangement, photocatalyst Dr. Tanoury began his career in the pharmaceutical industry in 1992 as a Medicinal Chemist at the Burroughs-Wellcome Company in North Carolina. In 1996, he moved to Sepracor, Inc. in Massachusetts to start a career as a process development chemist. He moved to Vertex Pharmaceuticals in 2001 where he is currently a Senior Scientific Fellow in the Process Chemistry Department. Prior to starting his industrial career, Dr. Tanoury was a graduate student under the direction of Professor Barry M. Trost, earning his Ph.D. from Stanford University in 1989. This was followed by a National Institutes of Health postdoctoral fellowship at Harvard University from 1989-1992 in the labs of Professor E. J. Corey. In addition to synthetic organic chemistry and developing chemical processes for the manufacture of API, Dr. Tanoury's interests include understanding and probing chemical reactions using state-ofthe-art technology, and studying reaction mechanisms and chemical properties (ground and excited state) using theoretical/computational methods.

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Intramolecular Cycloadditions of Photogenerated Azaxylylenes with Oxadiazoles Provide Direct Access to Versatile Polyheterocyclic Ketopiperazines Containing a Spiro-oxirane Moiety

Cited by 28 publications

References 19 publications

Chirality and Excited State Proton Transfer: From Sensing to Asymmetric Synthesis

Chirality and Excited State Proton Transfer: From Sensing to Asymmetric Synthesis

Synthesis of 5-substituted-3H-[1,3,4]-oxadiazol-2-one derivatives: a carbon dioxide route (CDR)

Photochemical Synthesis of Azaheterocycles

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