Theoretical investigation of the mechanism of DMAP-promoted [4 + 2]-annulation of prop-2-ynylsulfonium with isatoic anhydride

2022 ◽  
pp. 1-9
Author(s):  
Nan Lu ◽  
Hui Liang ◽  
Chengxia Miao ◽  
Xiaozheng Lan ◽  
Ping Qian

The mechanism for DMAP-promoted [4 + 2]-annulation of prop-2-ynylsulfonium with isatoic anhydride is investigated using the M06-2X functional. The reaction comprises isomerization of prop-2-ynylsulfonium in stage 1. Stage 2 includes DMAP-promoted deprotonation, nucleophilic addition, ring opening, and decarboxylation. Three steps of intramolecular cycloaddition, DMAP-promoted protonation, and dealkylation occur in stage 3, generating methylated DMAP and neutral thioether, which undergo double-bond isomerization to yield 3-methylthio-4-quinolone. The ability of DMAP to promote the reaction lies in the barrier decrease for alkyne isomerization, deprotonation/protonation of allenes, and dealkylation as effective bases for transferring protons and methyl groups. The roles of prop-2-ynylsulfonium and isatoic anhydride were demonstrated to be C2 and C4 synthons via Multiwfn analysis on the frontier molecular orbital. An alternative path was also confirmed by the Mayer bond order of the vital transition states.

2009 ◽  
Vol 62 (2) ◽  
pp. 157 ◽  
Author(s):  
Rong-Xiu Zhu ◽  
Ruo-Xi Wang ◽  
Dong-Ju Zhang ◽  
Cheng-Bu Liu

The thiourea-catalyzed methanolysis of d-lactide, a model system for the initiation and propagation of the organocatalyzed ring-opening polymerization (ROP) of lactide, has been studied by performing density functional theory calculations. Both the catalyzed and uncatalyzed reactions are explored along two possible pathways: one involves the stepwise addition–elimination pathway and the other is related to the concerted pathway. It is found that the reaction without the presence of the catalyst is difficult because the barrier involved is as high as 176 kJ mol–1. With the aid of a thiourea catalyst, the barrier is reduced to 88 kJ mol–1 with a preference for the stepwise addition–elimination mechanism over the concerted one. The role of the catalyst has been rationalized by analyzing the frontier molecular orbital interactions between the catalyst and substrates and by performing natural population analysis. Finally, another mechanism involving acyl transfer is discussed for the thiourea-catalyzed ROP.


2022 ◽  
Author(s):  
Zhi-Gang Yin ◽  
Xiong-Wei Liu ◽  
Hui-Juan Wang ◽  
Min Zhang ◽  
Xiong-Li Liu ◽  
...  

A highly efficient synthesis of structurally diverse ortho-acylphenol–diindolylmethane hybrids 3 using carboxylic acid-activated chromones as versatile synthetic building blocks is reported here for the first time, through 1,4-nucleophilic addition and followed by a decarboxylation and pyrone ring opening reaction process.


Synthesis ◽  
2019 ◽  
Vol 51 (16) ◽  
pp. 3160-3170
Author(s):  
Srilaxmi M. Patel ◽  
Harika Chada ◽  
Sonali Biswal ◽  
Sonika Sharma ◽  
Duddu S. Sharada

A copper-catalyzed intramolecular α-C–H amination has been developed for the synthesis of quinazolin-4(3H)-one derivatives from commercially available isatoic anhydride and primary and secondary benzylamines via ring-opening cyclization (ROC). This method shows good functional group tolerance and allows access to a range of 2-aryl, 2-alkyl, and spiroquinazolinone derivatives. However, 2-methylquinazolin-4(3H)-one was synthesized from 2-amino-N-isopropylbenzamide by C–C bond cleavage, and N-benzyl-2-(methylamino)benzamide afforded 1-methyl-2-phenylquinazolin-4(1H)-one along with 2-phenylquinazolin-4(3H)-one by N–C bond cleavage for aromatization. It is the first general method to construct the potentially useful 2-methylquinazolin-4(3H)-one by copper-catalyzed intramolecular C–H amination. Also this ROC strategy has been successfully applied to the synthesis of quinazolinone alkaloid rutaecarpine.


ChemInform ◽  
2015 ◽  
Vol 46 (11) ◽  
pp. no-no
Author(s):  
Hongnan Sun ◽  
Chao Yang ◽  
Run Lin ◽  
Wujiong Xia

1999 ◽  
Vol 77 (5-6) ◽  
pp. 922-933 ◽  
Author(s):  
Tina L Amyes ◽  
Tadeusz Mizerski ◽  
John P Richard

The addition of a pair of ortho-methyl groups to ring-substituted cumyl derivatives to give the corresponding 2,6-dimethylcumyl derivatives X-1-Y leads to modest (<5-fold) changes in the observed rate constant for reaction in 50:50 (v:v) trifluoroethanol-water (I = 0.50, NaClO4). The reactions of X-1-Y proceed by a stepwise mechanism through the liberated 2,6-dimethylcumyl carbocations X-2 that partition between nucleophilic addition of solvent and deprotonation to give good yields ([Formula: see text] 67%) of the corresponding 2-(2,6-dimethylaryl)propenes X-3. The carbocations X-2 are also trapped by nucleophilic addition of azide ion to give good yields ([Formula: see text] 68% at [N3-] = 0.50 M) of the corresponding 2,6-dimethylcumyl azides X-1-N3. In the presence of high concentrations of azide ion there are constant limiting yields of the alkenes X-3, which shows that X-2 also undergo significant reactions with azide ion as a Brønsted base. The product rate constant ratios for partitioning of the 2,4,6-trimethylcumyl carbocation Me-2 between reaction with azide ion as a Lewis and a Brønsted base, kaz/kB, the nucleophilic addition of azide ion and solvent, kaz/ks (M-1), and deprotonation by solvent, kaz/ke (M-1), were combined with (kaz + kB) = 5 × 109 M-1 s-1 for the diffusion-limited reaction of azide ion to give absolute rate constants for the reactions of Me-2. The data show that the addition of a pair of ortho-methyl groups to the 4-methylcumyl carbocation to give the sterically hindered Me-2 results in a 70-fold decrease in the rate constant for nucleophilic addition of solvent to the benzylic carbon, but a 60-fold increase in the rate constant for deprotonation of the carbocation by solvent.Key words: carbocation, ortho-substituent effects, steric effects, solvolysis, elimination.


2016 ◽  
Vol 29 (6) ◽  
pp. 2435-2444 ◽  
Author(s):  
James Stevenson ◽  
Blaire Sorenson ◽  
Varun Hari Subramaniam ◽  
James Raiford ◽  
Petr P. Khlyabich ◽  
...  

2006 ◽  
Vol 10 (07) ◽  
pp. 953-961 ◽  
Author(s):  
Chen-Hsiung Hung ◽  
Chia-Chi Liaw ◽  
Wei-Ming Chin ◽  
Gao-Fong Chang ◽  
Chuan-Hung Chuang

The nitration of free-base N -confused porphyrin led to a novel 5,10-meso-dihydroxy- N -confused porphodimethene and an open-ring N -confused violinoid. The results support nitration occurring first, followed by nucleophilic addition of a hydroxyl group and a parallel reaction of oxygenolysis to cause the ring-opening. The nitro group substituted at the inner carbon of the inverted pyrrole ring is located on both the porphodimethene and violinoid. In the case of the porphodimethene, two dihydroxyl groups with υ( OH ) at 3404 cm−1 are arranged in a syn conformation at the same side with the nitro group. The violinoid exhibits υ( C = O ) at 1659 cm−1. NMR and structure determination suggest that oxygenolysis occurs selectively at the C=C bond between the α-pyrrole and meso carbon closest to the amino NH of the inverted pyrrole ring. The single crystal structure of porphodimethene gave a 50% disorder between the peripheral nitrogen and carbon atom on the inverted pyrrole ring, while a dimeric structure assembled through hydrogen bonding interactions was observed in the crystal lattice of the violinoid.


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