3-( E )-But-2-enoxy-1,2-benzisothiazole 1,1-dioxide: unusual C—O—C ether bond l...

• Author(s): Barkley, J. V. ; Cristiano, Maria Lurdes Santos ; Johnstone, Robert A. W. ; Loureiro, Rui M. S.
• Date: 1997
• Persistent ID: http://hdl.handle.net/10400.1/4237
• Origin: Sapientia - Universidade do Algarve
• Document Type: Article
• Language: English

Description

Ethers such as the title compound, C~HIINO3S, (1), rearrange thermally to give N-allyl isomers, (2), in high yield. The X-ray structure determination of the title ether shows a central C--O--C linkage which has one very short (notional) C--O single bond and one exceptionally long single C--O bond. The thermal migration of allyl from the O to the N atom involves the breaking of one of the ether bonds in (1) and a shortening of the other as it becomes a formal carbonyl group in the product (2). The rearrangement is thus considerably assisted by the ground-state structure of the starting ether, in which the bond to be broken is already stretched and the one that is to form a carbonyl group is already a substantial partial double bond.