- Lewis Acid-Catalyzed [4+2] Annulation between Propargylic Alcohols with Benzo[d]isoxazoles
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An unprecedented copper(II) trifluoromethanesulfonate-catalyzed [4+2] cascade annulation of propargylic alcohols with benzo[d]isoxazoles proceeds through a sequential ring opening/Meyer–Schuster rearrangement/intermolecular cyclization. This protocol, whi
- Han, Ya-Ping,Li, Xue-Song,Sun, Zhou,Zhu, Xin-Yu,Li, Ming,Song, Xian-Rong,Liang, Yong-Min
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- An efficient Benzannulation protocol for the synthesis of 9,9-Diphenyl-9H-fluorenols using Intramolecular Allene Friedel–Crafts Annulation
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Herein we report a one-pot cascade benzannulation protocol for the synthesis 9,9-diaryl-9H-fluorenol, a key structure of many important natural products which exhibit the significant biological activities particularly phosphodiesterase-4 (PDE4) inhibitory activity. This approach proceeds through the annulation of tert-propargyl alcohols with 2-methyl acetylacetone through an intramolecular allene Friedel–Crafts reaction using Ca(OTf)2 as the environmentally benign catalyst. Synthetic transformations of these compounds to useful materials are also presented here with the aid of cross-coupling and RCM reactions.
- Yaragorla, Srinivasarao,Rajesh
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- In Situ Generation of Allenes and their Application to One-Pot Assembly of Functionalized Fluoreno[3,2-b]furans by Calcium-Catalyzed, Regioselective, 3-Component Reactions
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We have developed a novel synthetic methodology for the preparation of tetra-annulated fluorenofurans and fluorenopyrans using calcium(II)-catalyzed one-pot, three-component reaction. In this reaction, tert-propargyl alcohols react with 1,3-dicarbonyls to form tetra-substituted allenes, which are subsequently undergoing regiodivergent annulation with sec-propargyl alcohols to produce the fluorene-fused furan compounds. Broad substrate scope, regioselectivity, gram-scale synthesis, and benzylic functionalization of products are some of the highlights of this protocol.
- Rajesh, Pallava,Yaragorla, Srinivasarao
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- Regiospecific formal [3 + 2] annulation of: Tert -propargyl alcohols with acyclic 1,3-diketones via the cycloisomerization of homoallenyl ketones
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A one-pot, regiospecific synthesis of dihydrofurans bearing a quaternary centre and tetrasubstituted furans is developed from the formal [3 + 2] annulation of tert-propargyl alcohols and 1,3-diketones under Ca(ii)/DBU conditions. The reaction proceeds through the SN2I mechanism to form homoallenyl ketone and a subsequent cycloisomerization to yield novel and new chemical entities of privileged scaffolds.
- Yaragorla, Srinivasarao,Rajesh
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- Ca(II)-Mediated Regioselective One-pot Sequential Annulation of Acyclic compounds to Polycyclic Fluorenopyrans
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Herein we report a facile synthesis of tetracyclic fluorenopyrans from simple acyclic reactants, propargyl alcohols and 3-methylpentane-2,4-dione under calcium catalysis. This one-pot, 3-component reaction proceeds through a sequential allene formation, F
- Yaragorla, Srinivasarao,Rajesh,Pareek, Abhishek,Kumar, Ankit
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- A metal-free tandem dehydrogenative α-arylation reaction of propargylic alcohols with 2-alkynylbenzaldoximes toward the synthesis of α-(4-bromo-isoquinolin-1-yl)-propenone skeletons
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A tandem reaction of 2-alkynylbenzaldoximes with propargylic alcohols has been developed for the synthesis of α-(4-bromo-isoquinolin-1-yl)-propenones. Employing 2-alkynylbenzaldoximes as a precursor in the presence of Br2 generates 4-bromo-isoquinoline-N-
- Abbasi Kejani, Alireza,Alatat, Khalil,Balalaie, Saeed,Bijanzadeh, Hamid Reza,Nikbakht, Ali
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supporting information
p. 579 - 583
(2022/02/01)
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- Calcium-Catalyzed Intramolecular Hydroamination-Deacylation Reaction of in situ formed β-Amino Allenes
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We have developed a simple, One-Pot, three-component reaction of tert-propargyl alcohols, primary amines and acyl ketones to synthesize fully substituted pyrroles and pyridine derivatives in good to excellent yields with large substrate diversity. An eco-friendly calcium catalyst catalyzes the reaction to form the key intermediate β-amino allene that undergoes subsequent Thorpe-Ingold effect assisted hydroamination and aromaticity driven deacylation reaction to yield fully substituted five and six-membered azacyclic compounds. (Figure presented.).
- Yaragorla, Srinivasarao,Latha, Dandugula Sneha,Rajesh, Pallava
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supporting information
p. 5486 - 5492
(2021/12/10)
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- Br?nsted Acid Promoted Thermal-Ring-Rearrangement of Fluorenopyrans to 2-(1H-Inden-3-yl)-9H-fluoren-3-ols Bearing Two All-Carbon-Quaternary Centres
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4-Aryl-fluorenopyrans bearing quaternary centre at C2 and C6 positions underwent a thermal-ring-rearrangement with a catalytic amount of pTsOH to furnish 2-(1H-inden-3-yl)-9H-fluoren-3-ols with two all carbon-quaternary centres, in which one is retained a
- Jose, K. V. Jovan,Khan, Tabassum,Praveen, Dudam,Rajesh, P.,Yaragorla, Srinivasarao
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supporting information
(2020/04/22)
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- Synthesis of 2-(Isoquinolin-1-yl)prop-2-en-1-ones via Silver(I)-Catalyzed One-Pot Tandem Reaction of ortho-Alkynylbenzaldoximes with Propargylic Alcohols
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The silver(I)-catalyzed reaction of ortho-alkynylbenzaldoximes with propargylic alcohols represents a new strategy for the divergent one-pot synthesis of 2-(isoquinolin-1-yl) prop-2-en-1-ones via tandem 6-endo-cyclization, 1,3-dipolar cycloaddition, and intramolecular dehydrative opening of the 2,3-dihydroisoxazole ring. This synthetic protocol tolerates a wide variety of ortho-alkynylbenzaldoximes and propargylic alcohols and affords the corresponding products in excellent yields.
- Nikbakht, Ali,Balalaie, Saeed,Breit, Bernhard
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supporting information
p. 7645 - 7648
(2019/10/14)
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- Br?nsted Acid-Mediated Formal [3+3] Annulation Between Propargylic Alcohols and 1,3-Diketones
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A Br?nsted acid-mediated formal [3+3] cascade annulation of propargylic alcohols with 1,3-diketones proceeds through a sequential Meyer?Schuster rearrangement/1,2-addition. This protocol, which has a wide scope and is conducted under an ambient atmosphere
- Han, Ya-Ping,Li, Xue-Song,Zhu, Xin-Yu,Sun, Zhou,Li, Ming,Wang, Yu-Zhao,Liang, Yong-Min
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supporting information
p. 870 - 874
(2017/12/26)
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- Transition-Metal-Free, Br?nsted Acid-Mediated Cascade Sequence in the Reaction of Propargyl Alcohols with Sulfonamido-indoles/-indolines: Highly Substituted δ- And α-Carbolines
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Br?nsted acid-mediated, transition-metal-free reaction of propargyl alcohols with sulfonamido-indoles/-indolines under mild conditions affords highly substituted δ- or α-carbolines in good to excellent yields. This protocol involves cascade reaction seque
- Selvaraj, Karuppu,Swamy, K. C. Kumara
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supporting information
p. 15043 - 15056
(2019/01/04)
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- Lewis Acid Catalyzed Cyclization of Propargylic Alcohols with 2-Vinylphenol
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An unprecedented Lewis acid catalyzed, protection-free, and high-efficiency synthesis of valuable 3,4-dihydro-2H-2,4-methanochromans via cycloaddition of propargylic alkynols with 2-vinylphenol is described. This cycloaddition protocol, which tolerates a
- Han, Ya-Ping,Song, Xian-Rong,Qiu, Yi-Feng,Li, Xue-Song,Zhang, Heng-Rui,Zhu, Xin-Yu,Liu, Xue-Yuan,Liang, Yong-Min
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supporting information
p. 3866 - 3869
(2016/08/16)
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- TMSCl-mediated synthesis of α,β-unsaturated amides via C-C bond cleavage and C-N bond formation of propargyl alcohols with trimethylsilyl azide
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A new method with high efficiency for the synthesis of α,β- unsaturated amides from the easily prepared propargyl alcohols and TMSN 3 using TMSCl as an acid promoter is developed. A wide variety of α,β-unsaturated amides were produced in moderate to excellent yields. Mechanistic studies indicate that this transformation involves TMSCl-mediated allenylazide intermediate formation, C-C bond cleavage, and C-N bond formation. Significantly, this reaction shows good functional group compatibility and high regioselectivity, with a relatively short reaction time and inexpensive reagents.
- Song, Xian-Rong,Song, Bo,Qiu, Yi-Feng,Han, Ya-Ping,Qiu, Zi-Hang,Hao, Xin-Hua,Liu, Xue-Yuan,Liang, Yong-Min
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p. 7616 - 7625
(2014/09/16)
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- The rubrenic synthesis: The delicate equilibrium between tetracene and cyclobutene
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Herein we describe the synthesis of new substituted tetraaryltetracenes, obtained by the dimerization of triarylchloroallenes, prepared from propargyl alcohols. The propargyl alcohols were prepared by two different synthetic strategies and then the alcohols were treated to obtain the corresponding acenes. In addition to the expected tetracene derivatives, we observed the formation of bis(alkylidene)cyclobutenes. When strong electron-donating substituents were present, the main product was the cyclobutene. We discuss a reaction mechanism that accounts for the formation of the cyclobutenes.
- Braga, Daniele,Jaafari, Abdelhafid,Miozzo, Luciano,Moret, Massimo,Rizzato, Silvia,Papagni, Antonio,Yassar, Abderrahim
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experimental part
p. 4160 - 4169
(2011/10/01)
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- Efficient synthesis of di- and trisubstituted 2-aryloxazoles via ytterbium(III) triflate catalyzed cyclization of tertiary propargylic alcohols with aryl amides
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An efficient synthetic method to prepare di- and trisubstituted 2-aryloxazoles based on Yb(OTf)3 catalyzed cyclization of trisubstituted propargylic alcohols with aryl amides is described. The reaction was accomplished in moderate to excellent product yields and with complete regioselective control. The mechanism is suggested to involve activation of the starting alcohol by the metal catalyst that results in its ionization. Subsequent cyclization of this newly generated carbocationic species with the aryl amide then affords the oxazole. In view of the mild conditions along with the low cost, commercially availability of Yb(OTf)3 and its high tolerance to air and moisture, the present synthetic approach offers an operationally simplistic and convenient route to this important aromatic heterocycle.
- Zhang, Xiaoxiang,Teo, Wan Teng,Chan, Philip Wai Hong
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supporting information; experimental part
p. 331 - 337
(2011/02/17)
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- Bronsted acid catalyzed cyclization of propargylic alcohols with thioamides. Facile synthesis of Di- and trisubstituted thiazoles
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Figure presented. A general and efficient method to prepare 2,4-di- and trisubstituted thiazoles via p-TsOH·H2O-catalyzed cyclization of trisubstituted propargylic alcohols with thioamides is described. The reaction was accomplished in moderate to excellent product yields under mild conditions that did not require the exclusion of air and moisture and offers an operationally simplistic and convenient route to this synthetically useful aromatic heterocycle.
- Zhang, Xiaoxiang,Teo, Wan Teng,Sally,Chan, Philip Wai Hong
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supporting information; experimental part
p. 6290 - 6293
(2010/11/18)
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- Ytterbium(III) triflate catalyzed tandem friedel-crafts alkylation/hydroarylation of propargylic alcohols with phenols as an expedient route to indenols
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A method to prepare indenols efficiently by ytterbium(III) triflate catalyzed tandem Friedel - Crafts alkylation/hydroarylation of propargylic alcohols with phenols is described. The reaction was accomplished In moderate to excellent yields and regioselectivity under mild conditions and offers a straightforward and convenient one step synthetic route to bioactive indenols and its derivatives.
- Zhang, Xiaoxiang,Teo, Wan Teng,Chan, Philip Wai Hong
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supporting information; experimental part
p. 4990 - 4993
(2009/12/28)
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