Beilstein J. Org. Chem.2015,11, 504–513, doi:10.3762/bjoc.11.57
=S ylides bearing at least one acyl group is identified as the 1,5-electrocyclization into 1,3-oxathioles. However, in the case of diazomalonates, the dominating process is 1,3-cyclization into thiiranes followed by their spontaneous desulfurization yielding the corresponding alkenes. Finally
stage of the cycloaddition process.
Keywords: diazocarbonyl compounds; 1,3-dipolar cycloaddition; 1,3-oxathioles; thiiranes; thiocarbonyl ylides; thioketones; Introduction
Dipolar cycloadditions of diazo compounds have been of great interest for a long time as they provide a means for the preparation
diazodiketones were essentially indifferent to aromatic and aliphatic thioketones under similar reaction conditions (Scheme 1) [14][15][19][20][21].
Generally, the main reaction products formed in these reactions were 1,3-oxathioles 3. However, in some cases, thiiranes 4 and alkenes 5 were isolated from the
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Graphical Abstract
Scheme 1:
The key experimental results on the DDC 1 reactions with thioketones 2 [19-21].
Beilstein J. Org. Chem.2013,9, 2751–2761, doi:10.3762/bjoc.9.309
react at room temperature with cycloaliphatic thioketones, e.g. 2,2,4,4-tetramethyl-3-thioxocyclobutanе-1-one and adamantanethione, via a cascade process in which the key step is a 1,5-electrocyclization of the intermediate thiocarbonyl ylide leading to tetrasubstituted spirocyclic 1,3-oxathioles. The
-oxathiole to alkene were performed at the DFT PBE1PBE/6-31G(d) level.
Keywords: 1,3-dipolar electrocyclization; 1,5-dipolar electrocyclization; 1,3-oxathioles; thiocarbonyl ylides; thiiranes; thioketones; Introduction
Aryl- and alkylsubstituted thioketones exhibit high 1,3-dipolar reactivity towards
diazodicarbonyl compounds with arylsubstituted (aromatic) thioketones to establish their suitability for the preparation of 1,3-oxathioles and other sulfur-containing heterocycles [7][8]. The main goal of the present study was to investigate the scope and limitations of cycloaddition reactions of 2-diazo-1,3
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Graphical Abstract
Figure 1:
Thioketones 1 and diazodicarbonyl compounds 2.