1,2,4-Oxadiazoles from cycloreversions of oxadiazabicyclo[3.2.0]heptenes: 1-azetines as thiocyanate equivalents

Abstract

Leave this area blank for abstract info.

2-Methylsulfanylbenzo[f]isoquinoline

“…2-Methylthio-4-(naphth-2-yl)-1-azetine 5 (Scheme 1) has been synthesized by us before [9,10] and used in cycloaddition reactions. Previously, the 1-azetine was obtained by alkylation of the readily available [9,10] thiolactam 7, as shown in Scheme 1.…”

“…Previously, the 1-azetine was obtained by alkylation of the readily available [9,10] thiolactam 7, as shown in Scheme 1. When this reaction mixture is worked up and purified immediately, the 1-azetine is the major product, as already reported [9,10].…”

“…Previously, the 1-azetine was obtained by alkylation of the readily available [9,10] thiolactam 7, as shown in Scheme 1. When this reaction mixture is worked up and purified immediately, the 1-azetine is the major product, as already reported [9,10]. However, we have now found that when the crude 1-azetine reaction mixture from the reaction of thiolactam 7 with trimethyloxonium tetrafluoroborate is left overnight rather than used immediately, the 1-azetine is not the isolated product, but rearranges to give 2-methylthiobenzo[f]isoquinoline 4 (35% from 7) instead.…”

Synthesis, conformation and antiproliferative activity of isothiazoloisoxazole 1,1-dioxides

“…No reactions of the imine present in the thiazete 1,1-dioxide (5a) were observed, and the starting material was returned unchanged in all cases, a huge disappointment given that we had shown that the imine within the 1-azetine system reacts easily with both nitrile oxides and cyclopropenones. [21][22][23][24] Other 1,3-dipoles (nitrile ylides, nitrilimines, nitrones, aryl azides and azomethine ylides) and dienes were found to be similarly unreactive. Interestingly, when the cyclopropenone reaction was attempted in the presence of a Lewis acid, a reaction was observed.…”

“…25 Nonetheless, we have shown that 1-azetines are able to act as precursors for the synthesis of benzoisoquinolines, 21 homotropane related heterocycles 22 and pyridines 23 via a formal [3+2]-cycloaddition reaction with cyclopropenones (which act as all-carbon 1,3-dipole equivalents) as well as acting as dipolarophiles for the synthesis of 1,2,4-oxadiazoles 24 via reaction with nitrile oxides. As a result of these successes, and given our interest in the β-sultam nucleus, we wished to explore the chemistry of the unsaturated β-sultam system, the thiazete 1,1-dioxide (4).…”