- Studies on chromone derivatives: regioselective 1,3-dipolar and 1,4-cycloaddition reactions of 3-cyano-4H-1-benzopyran-4-thione
-
1,3-Dipolar cycloaddition reactions of 3-cyano-4H-1-benzopyran-4-thione 1 with nitrilimines 3, nitrile oxides 7 and aldonitrones 8 yielded regioselective cycloadducts involving the thione function.In the latter two classes, the unstable cycloadducts fragmented to yield 3-cyanochromone 11 and isothiocyanate 12 or thioamide 13, respectively.In contrast, dienamines 14 preferred to react at the carbon-carbon double bond in a 1,4-cycloaddition yielding xanthione (9H-xanthene-9-thione) 16 by elimination of HCN and the amine moiety.Keywords: 1,3-dipolar cycloaddition / 1,4-cycloaddition / 4H-1-benzopyran-4-thione / nitrilimine / nitrile oxide / nitrone
- Sain, Bir,Prajapati, Dipak,Mahajan, Asha R,Sandhu, Jagir S
-
p. 313 - 316
(2007/10/02)
-
- SOME NOVEL ASPECTS OF REGIOSELECTIVITY IN 1,3 DIPOLAR CYCLOADDITIONS OF 4H-1-BENZOPYRAN-4-THIONE
-
4H-1-Benzopyran-4-thione (1) reacted smoothly with nitrilimines (3a-e) to afford regioselective cycloadducts (4a-e) in good yields.In contrast,benzonitrile oxide (6) and aldonitrones (7a-d) reacted preferentially at the thione function.The unstable cycloadduct (8) or (9) ruptured to give as isolable products chromone (10) and phenyl isothiocyanate (11) and the thioamides (12a-d).This indirectly proves the site of attack of the dipole at the thione group.
- Baruah, Arpan K.,Prajapati, Dipak,Sandhu, Jagir S.
-
p. 6137 - 6142
(2007/10/02)
-
- Utilization of thiocarbonyl transfer reagents. Preparation of thioamides, mercapto esters, and thiapyran derivatives
-
The reaction of 1,1'-thiocarbonyldiimidazole and 1,1'-thiocarbonylbis(1,2,4-triazole) with several aldonitrones has been found to afford thioamides in good yield.Several 1,1'-thiocarbonylbisazoles, which have been shown to undergo Diels-Alder additions wi
- Harpp, David N.,MacDonald, J. Gavin,Larsen, Charles
-
p. 951 - 957
(2007/10/02)
-
- SYNTHESIS OF THIOAMIDES FROM ALDONITRONES UTILIZING THIOCARBONYL TRANSFER REAGENTS
-
The reaction of 1,1'-thiocarbonyldiimidazole and 1,1'-thiocarbonylbis(1,2,4-triazole) with several aldonitrones has been found to afford thioamides in good yield.The effect of solvent polarity and base is discussed.
- Harpp, David N.,MacDonald J. Gavin
-
p. 4927 - 4930
(2007/10/02)
-