Studies on heterocyclic enaminonitriles. VI. Synthesis of 2-amino-3-cyano-4,5-dihydrofurans.

Journal of Heterocyclic Chem

Yamazaki

Tomioka

2002

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Section: Methodsmentioning

confidence: 99%

Synthesis of dihydrofuro[2,3‐b]pyridines by the reaction of 2‐amino‐4,5‐dihydro‐3‐furancarbonitriles with α,β‐unsaturated carbonyl compounds

Journal of Heterocyclic Chem

Yamazaki

Tomioka

2002

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“…1,25.2,25.4,25.5,25.67,25.73 (CH 2 ,5.30;N,12.27. Found: C,68.33;H,5.38;N,12. General Procedure for the Preparation of 1-Acyl-2-oxo-3-pyrrolidinecarbonitriles 2.…”

Section: -Cyclopropanecarboxamido-45-dihydro-3-furancarbonitrile (1b)mentioning

confidence: 99%

“…The starting compounds, 2-acylamino-4,5-dihydro-3furancarbonitriles 1b-j, were prepared by reaction of 2-amino-4,5-dihydro-3-furancarbonitrile [12] with acyl chlorides in pyridine. The 1 H nmr spectra of 1d, f-i in deuteriochloroform indicate that 1d, f-i consist of approximately a 7:3 tautomeric mixture of the enamine A and the imine B forms.…”

mentioning

confidence: 99%

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Synthesis of 1-acyl-2-oxo-3-pyrrolidinecarbonitriles by the reaction of 2-acylamino-4,5-dihydro-3-furancarbonitriles with sodium iodide

Yamagata

Okabe

Journal of Heterocyclic Chemistry

et al. 2005

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The reaction of 2‐acylamino‐4,5‐dihydro‐3‐furancarbonitriles 1 with sodium iodide in N,N‐dimethyl‐formamide gave the corresponding 1‐acyl‐2‐oxo‐3‐pyrrolidinecarbonitriles 2 in good yields. Successive treatment of 1 with titanium(IV) chloride and potassium carbonate resulted in the formation of N‐acyl‐1‐cyanocyclopropanecarboxamides 4. The same compounds 2 were also obtained by treatment of 4 with sodium iodide. The starting compounds 1 were synthesized by the reaction of 2‐amino‐4,5‐dihydro‐3‐furan‐carbonitrile with acyl chlorides in pyridine.

“…Therefore, we examined the reaction of 1a with ethyl acetoacetate in the presence of tin(IV) chloride and triethylamine, and found that the reaction proceeded smoothly to give 2a. The present paper deals with the reaction of 1a-c and 2-benzamido-4,5-dihydro-3-furancarbonitriles 4a-c [14] with active methylene compounds.…”

mentioning

confidence: 99%

Synthesis of 5,6‐dihydrothieno(and furo)pyrimidines bearing an active methine group at the 4‐position

Journal of Heterocyclic Chem

Yamagata

Yamazaki

2001

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The reactions of 2-benzamido-4,5-dihydro-3-thiophene(and -3-furan)carbonitriles (1a-c and 4a-c) with ethyl acetoacetate in the presence of tin(IV) chloride and triethylamine provided the corresponding ethyl 2-(5,6-dihydro-2-phenylthieno(and furo) [2,3-d]pyrimidin-4-yl)-3-oxobutanoates (2a-c and 9a-c). Similarly, compounds 1a-c and 4a-c reacted with dialkyl malonates to give the corresponding dialkyl(5,6-dihydro-2-phenylthieno(and furo) [2,3-d]pyrimidin-4-yl)propanedioates (5a-c, 6a-c, 10a-c and 11a-c). J. Heterocyclic Chem., 38, 269 (2001).In search of new methods [1][2][3][4] for synthesizing 5,6-dihydrothieno[2,3-d]pyrimidines from 2-amino-4,5-dihydro-3-thiophenecarbonitriles, we showed that 2-benzamido-4,5-dihydro-3-thiophenecarbonitrile (1a) [5] reacts with malononitrile in the presence of sodium hydride to give the malononitrile derivative [3]. This reaction probably occurs via addition of the cyano group of 1a to malononitrile to form the intermediate β-enaminonitrile A, which undergoes cyclization to give the malononitrile derivative. However, when 1a was treated with active methylene compounds lacking cyano group such as ethyl acetoacetate and diethyl malonate under the same conditions, no reaction occurred, and 1a was recovered unchanged. Hence, in order to overcome this limitation, we attempted to find the reaction conditions for the reaction of 1a with ethyl acetoacetate.Tin(IV) chloride has been shown to facilitate the carboncarbon bond formation between the cyano group of nitriles and active methylene compounds [6][7][8][9][10][11][12]. This reaction suggests the possibility that when 1a is treated with ethyl acetoacetate in the presence of tin(IV) chloride, the intermediate β-enaminoester B initially formed may undergo cyclization to furnish the expected 2a. Although the reaction of 1a with ethyl acetoacetate in the presence of tin(IV) chloride gave the 4-amino-2,3-dihydrothieno[2,3-b]-pyridine derivative 3 [13] in 44% yield, the desired 2a could not be isolated. Iimori and co-workers [7] reported that this carbon-carbon bond formation is successfully effected by using a combination of Lewis acid and tertiary amine. Therefore, we examined the reaction of 1a with ethyl acetoacetate in the presence of tin(IV) chloride and triethylamine, and found that the reaction proceeded smoothly to give 2a. The present paper deals with the reaction of 1a-c and 2-benzamido-4,5-dihydro-3-furancarbonitriles 4a-c [14] with active methylene compounds.When a mixture of 1a-c, ethyl acetoacetate (1.5 equivalents), triethylamine (1.5 equivalents) and tin(IV) chloride (3 equivalents) in 1,2-dichloroethane was refluxed, 2a-c were obtained in moderate yields. In a similar fashion, the reaction of 1a-c with diethyl and dimethyl malonates resulted in the formation of the corresponding malonic ester derivatives 5a-c and 6a-c in good yields. The 1 H nmr spectra of 2a and 2b in deuteriochloroform show two singlets at near δ 2.00 and δ 2.40 for acetyl groups, a singlet at near δ 4.80 for a methine and a singlet at near δ 13.20 for ...