On the mechanism of formation of glycofurano[2,1-d]-imidazolidin-2-ones. Reaction of 2-amino-2-deoxyheptopyranoses with isocyanates.
摘要:
Reaction of 2-aminosugars with isocyanates has been extended to other higher-carbon sugars. Ureido derivatives or, in most cases, monocyclic structures can be easily isolated. Importantly, the last substances display a relative trans disposition between the substituents at C-4 and C-5 of the heterocyclic ring, as a consequence of a rapid cis-trans isomerisation in acidic media. This stereochemical feature ensures (he stereocontrolled ring closure to give exclusively cis-fused glycofuranose systems. In the light of these results, some related reactions have been revised.
On the mechanism of formation of glycofurano[2,1-d]-imidazolidin-2-ones. Reaction of 2-amino-2-deoxyheptopyranoses with isocyanates.
摘要:
Reaction of 2-aminosugars with isocyanates has been extended to other higher-carbon sugars. Ureido derivatives or, in most cases, monocyclic structures can be easily isolated. Importantly, the last substances display a relative trans disposition between the substituents at C-4 and C-5 of the heterocyclic ring, as a consequence of a rapid cis-trans isomerisation in acidic media. This stereochemical feature ensures (he stereocontrolled ring closure to give exclusively cis-fused glycofuranose systems. In the light of these results, some related reactions have been revised.