603-72-5Relevant articles and documents
Multiple Fluorescences. 6. The Case of 1,8-Naphthosultam
Kanety, H.,Kosower, E. M.
, p. 3776 - 3780 (1982)
The emission from 1,8-naphthosultam (2H-naphthisothiazole 1,1-dioxide) (1a) is composed of two bands, one for the acid (λmax=480 nm) and one for the corresponding anion (2, λmax=600 nm).The fluorescence of both 1a and 2, as well as that of the N-methyl- and N-ethyl-1,8-naphthosultams (1b and 1c), has a modest sensitivity to solvent polarity.The ground-state pKa for 1a is 6.2, with pKa* of -3.0.The proton transfer rate for 1a to water is >5xE10 s-1, from the rise time of anion fluorescence by picosecond pulse techniques.The fluorescence lifetimes for 1a and 2 are 16 (Φf = 0.37, dioxane) and 1.4 (Φf = 0.005, H2O pH 10) ns, respectively.
General synthetic approach towards annelated 3a,6-epoxyisoindoles by tandem acylation/IMDAF reaction of furylazaheterocycles. Scope and limitations
Zubkov, Fedor I.,Nikitina, Eugenia V.,Galeev, Timur R.,Zaytsev, Vladimir P.,Khrustalev, Victor N.,Novikov, Roman A.,Orlova, Daria N.,Varlamov, Alexey V.
, p. 1659 - 1690 (2014/02/14)
An efficient and versatile one-pot synthesis of 3,6a-epoxyisoindoles annelated with oxazine, oxazole, thiazine, thiazole, pyrimidine fragments and with their benzoannelated analogues is presented. The method is based on tandem N-acylation/intramolecular cycloaddition (the intramolecular Diels-Alder reaction of furan, IMDAF) reaction between α,β-unsaturated acid anhydrides and α-furyl substituted azaheterocycles. The latter can be easily prepared by condensation of diverse furfurals and 1,2- or 1,3-N,X-binucleophiles (aminoalcohols, aminothiols, diamines). The observed IMDAF reaction is stereoselective: exo-adducts are formed exclusively with large prevalence of one of the diastereoisomers. In most cases, the condensation/N-acylation/IMDAF reaction sequence may be carried out via a one-pot domino protocol. The scope and limitations of the proposed approach are thoroughly investigated. The obtained Diels-Alder adducts are attractive and useful substrates for further transformations. Fused isoindoles can be prepared from them in one-step by aromatization of the 7-oxabicyclo[2.2.1]heptene ring. Other transformations, including halogenation, ring cleavage, and Wagner-Meerwein skeletal rearrangement, are also demonstrated. The spatial structures of the obtained compounds have been established by X-ray diffraction analyses.
1,2,3-Benzoxathiazole 2,2-Dioxides: Synthesis, Mechanism of Hydrolysis, and Reactions with Nucleophiles
Andersen, Kenneth K.,Bray, Diana D.,Chumpradit, Sumalee,Clark, Michael E.,Habgood, Gregory J.,et al.
, p. 6508 - 6516 (2007/10/02)
The rate of base-induced hydrolysis of some five-membered cyclic sulfamates, X-3-(p-tolylsulfonyl)-1,2,3-benzoxathiazole 2,2-dioxides (1a, X = H; 1b, X = 5-Me; 1c, X = 5-t-Bu; 1d, X = 5-Br; 1e, X = 5-Cl; 1f, X = 5-Ac; 1g, X = 5-NO2; 8a, X = 6-NO2) were measured in aqueous acetonitrile.The hydrolyses occurred with cleavage of the endocyclic N-SO2 bond.A Hammett plot using ?m values for 1a-g and ?p for 8a had ρ = +2.20.Activation enthalpies and entropies were measured for 1a and for 3-methyl-1,2,3-benzoxathiazole 2,2-dioxide (10).Volumes of activation weredetermined for 1g and for 8a.The mechanistic profile for hydrolysis resembled that for the saponification of the analogous sultones and cyclic sulfates.These first examples of 1,2,3-benzoxathiazole 2,2-dioxides (1a-g, 8a) were prepared by treating N-(2-hydroxyphenyl)-p-toluenesulfonamides with sulfuryl chloride and triethylamine or by oxidizing the monoxide precursors using m-chloroperbenzoic acid.Treatment of 1a with potassium fluoride gave 1,2,3-benzoxathiazole 2,2-dioxide (9), which was methylated to give 10.Sulfamate 1a was treated with various nucleophilic reagents: phenyllithium, methyllithium, potassium fluoride, methylamine, tert-butylamine, and sodium methoxide.The first three attacked the tosyl sulfur atom and cleaved the exocyclic N-SO2 bond.The amines attacked the endocyclic sulfonyl sulfur atom and cleaved the endocyclic N-SO2 bond.Sodium methoxide attacked both sulfonyl groups.
