A facile synthesis of 5-[(arylamino)(cyano)methylene]-2,2- dimethyl-1,3- dioxane-4,6-diones

Article abstract of DOI:10.1016/S0040-4039(00)00073-3

Treatment of 5-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-2,2-dimethyl-1,3- dioxane-4,6-dione with primary arylamines in CH₂Cl₂ at rt gave 5- [(arylamino)(cyano)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones in excellent yields. The latter compounds were utilized for the preparation of 2-cyano-4-quinolinones. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4039(00)00073-3

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 41 (2000) 1943–1945
A facile synthesis of 5-[(arylamino)(cyano)methylene]-2,2-
dimethyl-1,3-dioxane-4,6-diones
Moon-Kook Jeon and Kyongtae Kim ∗
Department of Chemistry, Seoul National University, Seoul 151-742, South Korea
Received 1 November 1999; revised 5 January 2000; accepted 7 January 2000
Abstract
Treatment of 5-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione with primary aryl-
amines in CH2Cl2 at rt gave 5-[(arylamino)(cyano)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones in excellent
yields. The latter compounds were utilized for the preparation of 2-cyano-4-quinolinones. © 2000 Elsevier Science
Ltd. All rights reserved.
Keywords: cyano compounds; dioxanes; dithiazoles; pyrolysis.
In recent years flash vacuum thermolysis of (alkyl and arylamino)methylene derivatives of Meldrum’s
acid (1) has attracted much attention owing to its potential synthetic utility and much theoretical and
mechanistic interest in the formation of its products.1 Compounds 1 have been basically synthesized
by two different methods: displacement of the methoxy group of 2a with appropriate amines1a–c,e,j,m, 2
and displacement of the methylthio group from 2b or 2c by employing appropriate amounts of alkyl or
arylamines.1e–h,i, 3
In a continuation of our research program involving 4,5-dichloro-5H-1,2,3-dithiazolium chloride
(Appel’s salt) (3),4 we have found that 5-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-2,2-dimethyl-1,3-
dioxane-4,6-dione (4), prepared by the reaction of 3 with Meldrum’s acid by documented procedures,5
reacted with primary arylamines (2 equiv.) in CH2Cl2 at rt affording 5-[(arylamino)(cyano)methylene]-
2,2-dimethyl-1,3-dioxane-4,6-diones (5) in excellent yields. In order to trap HCl formed during the
reaction, which might cause decomposition of 4, an additional amount of arylamines was employed
∗
Corresponding author. Tel: 82 2 880 6636; fax: 82 2 874 8858; e-mail: kkim@plaza.snu.ac.kr (K. Kim)
0040-4039/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(00)00073-3
tetl 16372

1944
(Scheme 1).6 In contrast, the reaction with secondary arylamine, i.e., diphenylamine, under the same
conditions at either rt or reflux did not occur. Compound 4 was recovered quantitatively.
Scheme 1. (i) CH2CI2, rt, 40 min–9 days (ii) Ph2O, reflux or heat, 200–220°C, 3–5 min
Compounds 5 which have never been reported are readily converted into 2-cyano-4-quinolinones (6)
by heating either in diphenyl ether at reflux or without a solvent at 200 to 220°C for 3 to 5 min. Analogous
products such as 4-quinolinones having 2-alkyl, 2-aryl, 2-alkoxy, 2-methylthio, and 2-amino groups have
been obtained by flash vacuum thermolysis of the corresponding substituted anilinomethylene derivatives
of Meldrum’s acids.1c,f–h,j–k, 3,7 The structures of 5 and 6 were determined based on spectroscopic and
analytical data. Reaction times, mps, and yields of 5 and 6 are summarized in Table 1.
Table 1
Reaction times, mps, and yields of 5-[(arylamino)(cyano)methylene]-2,2-dimethyl-1,3-dioxane-4,6-
diones (5) and 2-cyano-4-quinolinones (6)
Acknowledgements
The authors are grateful for the financial support given by the Korean Research Foundation in the
program year of 1998.
References
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