Addition of Grignard Reagents to Quinolinium Salts:  Evidence for a Unique Redox Reaction between a 1,4- and a 1,2-Dihydroquinoline

Mani, Neelakandha S.; Chen, Penghui; Jones, Todd K.

doi:10.1021/jo990586b

Cited by 18 publications

(7 citation statements)

References 21 publications

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“…The first involves the treatment of formamidine 1 with trimethylsilyl trifluoromethanesulfonate to give the N ‐(trimethylsilyl)formamidinium salt 2 . The reaction was developed from known literature examples for triazole, pyridine,, pyrimidine, quinoline, imines, isoquinoline, and imidazole . We found that at a temperature of –60 to 0 °C in dichloromethane, formamidine 1 underwent a reaction with trimethylsilyl trifluoromethanesulfonate to afford N ‐silylformamidinium salt 2 (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

C‐Silyl‐N,N‐dialkyl‐N′‐arylformamidines: Synthesis and Reactions with Phosphorus(III) Chlorides

et al. 2016

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A method for the synthesis of new C‐silyl‐N,N‐dialkyl‐N′‐arylformamidines was developed. These derivatives were formed by the deprotonation of N‐(trimethylsilyl)formamidinium salts to give the corresponding N‐trimethylsilyl carbenes followed by a 1,2‐migration of the silyl group. The reactions of C‐silylformamidines with phosphorus(III) chlorides were then studied. The reactions between chlorodiphenylphosphane and the C‐silylformamidines readily afforded C‐phosphanylformamidines in high yields. The reactions of dichlorophosphanes and C‐silylformamidines yielded previously unknown phosphanes that feature two formamidine substituents. In the reaction with phosphorus trichloride, the sterically least encumbered formamidine gave a stable two‐coordinate compound through the formation of an intermediate tris(phosphane). The reactions of the sterically more encumbered formamidines led to the substitution of only two chlorine atoms to give a chlorophosphane or benzazaphosphole. The structures of key compounds were proven by X‐ray crystal structure analyses.

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Section: Resultsmentioning

confidence: 99%

C‐Silyl‐N,N‐dialkyl‐N′‐arylformamidines: Synthesis and Reactions with Phosphorus(III) Chlorides

et al. 2016

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“…The 1,2-dihydroquinolines, such as HD-1,2, are known to be quite stable toward additional hydride attack; [40] however, it easily undergoes a disproportionation to afford tetrahydroquinoline and quinoline through the in- www.chemeurj.org termediacy of 1,4-dihydroquinoline, which disproportionation reaction itself would also explain our labeling results. [41] To verify the involvement of a HD-1,4 intermediate in the metal-free catalytic cycle, we attempted to obtain indirect information about its existence. We reasoned that a deuterium exchange upon enamine-imine tautomerization (HD-1,4ÐHD-Im) can serve as a handle.…”

Section: Scheme 7 a Concise Synthesis Of Rac-cuspareine (15)mentioning

confidence: 99%

Catalytic Hydrogenation with Frustrated Lewis Pairs: Selectivity Achieved by Size‐Exclusion Design of Lewis Acids

Erős

Nagy

Hasan

et al. 2011

Chemistry A European J

156

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Catalytic hydrogenation that utilizes frustrated Lewis pair (FLP) catalysts is a subject of growing interest because such catalysts offer a unique opportunity for the development of transition-metal-free hydrogenations. The aim of our recent efforts is to further increase the functional-group tolerance and chemoselectivity of FLP catalysts by means of size-exclusion catalyst design. Given that hydrogen molecule is the smallest molecule, our modified Lewis acids feature a highly shielded boron center that still allows the cleavage of the hydrogen but avoids undesirable FLP reactivity by simple physical constraint. As a result, greater latitude in substrate scope can be achieved, as exemplified by the chemoselective reduction of α,β-unsaturated imines, ketones, and quinolines. In addition to synthetic aspects, detailed NMR spectroscopic, DFT, and (2)H isotopic labeling studies were performed to gain further mechanistic insight into FLP hydrogenation.

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“…In addition to the classical method for the synthesis of quinolines including Skraup, Friedländer, Pfitzinger synthesis, different new methods have been developed for the synthesis of quinolines by using metallic or organometallic catalyst and Lewis acids such as Ruthenium (III) chloride, Yb(OTf) 3 , W(CO) 5 (THF), BF 3 .OEt 2 , and etc . However, most of these methods suffer from harsh reaction conditions and the use of stoichiometric and expensive reagents.…”

Section: Introductionmentioning

confidence: 99%

An Unexpected Synthesis of 2,3,4‐Trisubstituted Quinolines from Imino‐Isatin and Acetylenic Esters Catalyzed by Pyridine as an Organocatalyst

et al. 2018

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In this paper we report an unexpected synthesis of the 2,3,4‐trisubstituted quinoline systems. The reaction between imino‐isatin (synthesized from the reaction of isatin and ammonia (2 M in MeOH)) and dialkylacetylenedicarboxylates proceeds in MeOH at room temperature in the presence of pyridine as an organocatalyst. The structures of all new compounds were corroborated spectroscopically (1H‐ and 13C‐NMR, and elemental analysis). A plausible mechanism for this type of reaction is proposed.

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Addition of Grignard Reagents to Quinolinium Salts: Evidence for a Unique Redox Reaction between a 1,4- and a 1,2-Dihydroquinoline

Cited by 18 publications

References 21 publications

C‐Silyl‐N,N‐dialkyl‐N′‐arylformamidines: Synthesis and Reactions with Phosphorus(III) Chlorides

C‐Silyl‐N,N‐dialkyl‐N′‐arylformamidines: Synthesis and Reactions with Phosphorus(III) Chlorides

Catalytic Hydrogenation with Frustrated Lewis Pairs: Selectivity Achieved by Size‐Exclusion Design of Lewis Acids

An Unexpected Synthesis of 2,3,4‐Trisubstituted Quinolines from Imino‐Isatin and Acetylenic Esters Catalyzed by Pyridine as an Organocatalyst

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