20026-96-4Relevant academic research and scientific papers
Synthesis of novel benzochromenes using triarylphosphines, alkyl X-phenylpropiolates and 2-hydroxy-1-naphthaldehyde
Gholami, Hamid Reza,Asghari, Sakineh
, p. 206 - 209 (2018)
The reactions of a series of alkyl X-phenylpropiolates with 2-hydroxy-1-naphthaldehyde and triphenylphosphine led to benzochromenes in moderate yields. When the reactions were performed in the presence of bis(4-methoxyphenyl)phenylphosphine instead of tri
Gold-catalyzed partial hydrogenation of activated alkynes mediated by triphenylphosphine
Cocoletzi-Xochitiotzi, Ana Patricia,Hernández-Hernández, Miguel,Medina-Mercado, Ignacio,Jiménez-Martínez, Williams De Jesús,Mastranzo, Virginia Maricela,Porcel, Susana
supporting information, p. 2379 - 2386 (2020/08/19)
Gold(I) can exhibit a cooperative effect with triphenylphosphine, accelerating the triphenylphosphine-mediated partial hydrogenation of activated alkynes. In this protocol, 3-arylpropiolates are selectively reduced to the Z -isomer when the aryl ring bears an electron-donor substituent, whereas 3-arylpropynones are reduced to the E-isomers.
Consecutive Three-Component Coupling-Addition Synthesis of β-Amino Enoates and 3-Hydroxypyrazoles via Ethyl 3-Arylpropiolates
Niedballa, Jonas,Reiss, Guido J.,Müller, Thomas J. J.
supporting information, p. 5019 - 5024 (2020/07/24)
Two consecutive three-component syntheses furnishing β-amino enoates or 3-hydroxypyrazoles based upon the Sonogashira alkynylation of aryl iodides and ethyl propiolate were established in mostly excellent yields. The ethyl 3-arylpropiolate intermediates are Michael systems which are suited for concatenation with conjugate addition or cyclocondensation giving access to libraries of 21 different β-amino enoates and 17 different 3-hydroxypyrazoles. The rotational barrier of β-pyrrolidino enoates was assessed by studying the coalescence of pyrrolidinyl protons in VT-NMR spectra of electronically different substituted derivatives showing that the electronic substituent effect on the aryl group does not affect the height of the rotational barrier. This indicates that the substituents are essentially oriented orthogonally to the plane of the β-pyrrolidino enoates.
Metal-Free Oxidative [5+1] Cyclization of 1,5-Enynes for the Synthesis of Pyrazine 1-Oxide
Xia, Xiao-Feng,Zhao, Mingming,He, Wei,Zou, Lianghua,San, Xinxin,Wang, Dawei
supporting information, p. 3621 - 3626 (2020/08/05)
A chemo-selective nitrosylation of 1,5-enynes via a sequence of NO radical incorporation and intramolecular radical cyclization was reported. The formation of two C?N bonds and one C?O bond make this [5+1] cycloaddition reaction an efficient approach to synthesize pyrazine 1-oxides in moderate to good yields. Metal-free, short reaction time and mild conditions render this strategy more practical, eco-friendly and convenient. Synthetic utility of this protocol is highlighted by scaffolds diversification. (Figure presented.).
Rhodium-catalyzed enantioselective decarboxylative alkynylation of allenes with arylpropiolic acids
Grugel, Christian P.,Breit, Bernhard
supporting information, p. 1066 - 1069 (2018/02/23)
A rhodium-catalyzed chemo-, regio-, and enantioselective intermolecular decarboxylative alkynylation of terminal allenes with arylpropiolic acids is reported. Employing a Rh(I)/(R)-Tol-BINAP catalytic system, branched allylic 1,4-enynes were obtained under mild conditions. The overall utility of this protocol is exemplified by a broad functional group compatibility.
A Parallel Approach to 7-(Hetero)arylpyrazolo[1,5- a]pyrimidin-5-ones
Schmitt, Daniel C.,Niljianskul, Nootaree,Sach, Neal W.,Trujillo, John I.
supporting information, p. 256 - 260 (2018/05/24)
A modular, two-pot assembly of 7-arylpyrazolo[1,5-a]pyrimidones from aryl/heteroaryl halides and aminopyrazoles in library format was developed. Sonogashira coupling of aryl bromides with triethyl orthopropiolate, followed by in situ orthoester hydrolysis
Phosphine-mediated partial reduction of alkynes to form both (E)- and (Z)-alkenes
Pierce, Brett M.,Simpson, Brittany F.,Ferguson, Kane H.,Whittaker, Rachel E.
supporting information, p. 6659 - 6662 (2018/09/29)
A mild, phosphine-mediated partial reduction of alkynyl carbonyls to the corresponding alkenes was developed. Tuning of the reaction conditions led to either the (E)- or (Z)-diastereomer with high selectivity. A range of alkynyl esters, amides, and ketones were reduced to form alkenes in good to high yields and with excellent functional group tolerance.
Gold(I)/Chiral N,N′-Dioxide–Nickel(II) Relay Catalysis for Asymmetric Tandem Intermolecular Hydroalkoxylation/Claisen Rearrangement
Li, Jun,Lin, Lili,Hu, Bowen,Zhou, Pengfei,Huang, Tianyu,Liu, Xiaohua,Feng, Xiaoming
supporting information, p. 885 - 888 (2017/01/13)
A highly efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a π-acidic gold(I) complex with a Claisen rearrangement catalyzed by a chiral Lewis acidic N,N′-dioxide–nickel(II) complex. A range of acyclic α-allyl β-keto esters were synthesized in high yields (up to 99 %) with good diastereoselectivities (up to 97:3) and excellent enantioselectivities (up to 99 % ee) under mild reaction conditions. These products can be easily transformed into optically active β-hydroxy esters, β-hydroxy acids, or 1,3-diols.
Gold-catalyzed Fluorination of Alkynyl Esters and Ketones: Efficient Access to Fluorinated 1,3-Dicarbonyl Compounds
Zeng, Xiaojun,Lu, Zhichao,Liu, Shiwen,Hammond, Gerald B.,Xu, Bo
supporting information, p. 4062 - 4066 (2017/11/30)
We developed an efficient synthesis of 2-fluoro-1,3-dicarbonyl compounds using readily available alkynyl ketones or esters as starting material. The key step is the insertion of hydrogen fluoride (HF) to the gold carbene intermediate generated from cationic gold catalyzed addition of N-oxides to alkynyl ketones or esters. This method gives excellent chemical yields and regioselectivity with good functional group tolerance. (Figure presented.).
Enantioselective Palladium-Catalyzed Oxidative Cascade Cyclization of Aliphatic Alkenyl Amides
Du, Wei,Gu, Qiangshuai,Li, Yang,Lin, Zhenyang,Yang, Dan
supporting information, p. 316 - 319 (2017/04/21)
The catalyst system of Pd(TFA)2/(S,S)-diPh-pyrox is reported to promote the highly efficient enantioselective oxidative cascade cyclization of alkene-tethered aliphatic acrylamides under mild aerobic conditions. A series of pyrrolizidine derivatives have been synthesized in good yield and excellent enantioselectivity. Deuterium-labeling experiments have revealed that the reaction proceeded through an anti-aminopalladation (anti-AP) pathway with high selectivity. The transition states for the anti-AP step have been calculated to account for the observed enantioselectivity.
