- Heterocycloalkynes Fused to a Heterocyclic Core: Searching for an Island with Optimal Stability-Reactivity Balance
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In the search for fundamentally new, active, stable, and readily synthetically accessible cycloalkynes as strain-promoted azide-alkyne cycloaddition (SPAAC) reagents for bioorthogonal bioconjugation, we integrated two common approaches: the reagent destab
- Balova, Irina A.,Danilkina, Natalia A.,Govdi, Anastasia I.,Khlebnikov, Alexander F.,Ryazantsev, Mikhail N.,Sharoyko, Vladimir V.,Shtyrov, Andrey A.,Tikhomirov, Alexander O.,Br?se, Stefan
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supporting information
p. 16519 - 16537
(2021/10/20)
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- Tetrahydroxydiboron-Promoted Radical Addition of Alkynols
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Tetrahydroxydiboron has previously been used as a borylation or reducing reagent in organic synthesis. Herein, we present a novel tetrahydroxydiboron-promoted radical addition of internal alkynes followed by intramolecular oxidation of alcohol through 1,5-hydrogen atom transfer. Preliminary mechanistic studies showed that the process might be initiated through N,N-dimethylformamide-assisted homolytic cleavage of tetrahydroxydiboron. This process provides a convenient synthesis of fluoroalkyl-substituted alkenes with a pendant aldehyde or ketone moiety.
- Sun, Ze-Ying,Zhou, Sen,Yang, Kai,Guo, Minjie,Zhao, Wentao,Tang, Xiangyang,Wang, Guangwei
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supporting information
p. 6214 - 6219
(2020/08/12)
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- Metal-Free Synthesis of 4-Chloroisocoumarins by TMSCl-Catalyzed NCS-Induced Chlorinative Annulation of 2-Alkynylaryloate Esters
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4-Chloroisocoumarins can be conveniently prepared from 2-alkynylaryloate esters via the activation of alkynes by electrophilic chlorine, generated in situ from N-chlorosuccinimide (NCS) in the presence of 10 mol % trimethylsilyl chloride (TMSCl), which leads to 6-endo-dig-selective chlorinative annulation to give the desired products in moderate to quantitative yields. The procedure employs readily available reagents and can be conveniently carried out on a wide scope of substrates under mild conditions (0 °C to rt). Furthermore, the reaction is scalable for gram-scale preparation of 4-chloroisocoumarins. Additionally, 4-bromo- and 4-iodoisocoumarins can be prepared in moderate to good yields by replacing NCS with N-bromosuccinimide (NBS) and N-iodosuccinimide (NIS), respectively.
- Norseeda, Krissada,Chaisan, Nattawadee,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Ruchirawat, Somsak
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p. 16222 - 16236
(2019/12/25)
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- Synthesis of 3-(carboxyarylalkyl)imidazo[2,1-f][1,2,4]triazines as potential inhibitors of AMP deaminase
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C-Ribosyl 1,2,4-triazolo[1,2,4]triazines which are able to undergo covalent hydration are of interest as potential inhibitors of AMP deaminase. In a search for compounds with improved bioavailability we have synthesized compounds in which the sugar has been replaced by carboxyarylalkyl based ribose phosphate mimics. The target carboxyarylalkyl imidazotriazines 11 and 12 were synthesized using a linear seven step sequence starting from simple benzoate derivatives. Alternatively, the hydroxyethyl imidazotriazine 39 is available in five steps and this synthon was used to prepare the imidazotriazines 34 and 48 in a short convergent manner.
- Kirkman, Joseph K.,Lindell, Stephen D.,Maechling, Simon,Slawin, Alexandra M. Z.,Moody, Christopher J.
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supporting information; experimental part
p. 4452 - 4459
(2009/02/07)
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- Development of synthetic routes to macrocyclic compounds based on the HSP90 inhibitor radicicol
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Short routes are reported to novel macrolides (e.g., 9, 12, 20) related to the HSP90 inhibitor radicicol.
- Atrash, Butrus,Cooper, Tracey S.,Sheldrake, Peter,Workman, Paul,McDonald, Edward
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p. 2237 - 2240
(2007/10/03)
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- Synthesis of isocoumarins and α-pyrones via electrophilic cyclization
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A variety of substituted isocoumarins and α-pyrones are readily prepared in excellent yields under very mild reaction conditions by the reaction of o-(1-alkynyl)benzoates and (Z)-2-alken-4-ynoates with ICl, I2, PhSeCl, p-O2NC6/
- Yao, Tuanli,Larock, Richard C.
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p. 5936 - 5942
(2007/10/03)
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- A Tandem Cyclization-Onium Ylide Rearrangement-Cycloaddition Sequence for the Synthesis of Benzo-Substituted Cyclopentenones
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A new annulation sequence leading to benzo-substituted cyclopentenones is effected by treating o-alkynyl-substituted α-diazoacetophenones containing tethered heteroatoms with Rh(II) carboxylates.The reaction involves addition of the initially formed keto
- Padwa, Albert,Kassir, Jamal M.,Semones, Mark A.,Weingarten, M.David
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- A comparative Study of the Decomposition of o-Alkynyl-Substituted Aryl Diazo Ketones. Synthesis of Polysubstituted β-Naphthols via Arylketene Intermediates
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The photochemical, thermal, and rhodium-catalyzed decomposition reactions of several closely related o-alkynyl or o-alkenyl α-diazoaceto- and propiophenone derivatives have been studied.The reaction outcome is markedly dependent upon the reaction conditions employed for nitrogen extrusion.Thermolysis or photolysis of o-alkynyl α-diazopropiophenone derivatives yields polysubstituted β-naphthols.These products are derived from Wolff rearrangement of the initially formed carbene to give an aryl ketene which undergoes intramolecular cyclization onto the o-alkynylsubstituent.In direct contrast to the thermal and photochemical results, Rh(II)-catalyzed decomposition yields products derived from direct attack of a rhodium carbenoid onto the tethered ?-system producing a vinyl carbenoid intermediate.Further reaction of the cyclized carbenoid with the starting diazo compound furnished a vinyl indenone which undergoes a rapid intramolecular Diels-Alder reaction to produce a novel dimer whose structure was elucidated by an X-ray crystal analysis.Replacement of the methyl group on the diazo center with a sterically less demanding hydrogen atom was also found to play an important role in controlling the outcome of the Rh(II)-catalyzed reaction.
- Padwa, Albert,Chiacchio, Ugo,Fairfax, David J.,Kassir, Jamal J.,Litrico, Angelo,at al.
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p. 6429 - 6437
(2007/10/02)
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