content_image/940626.jpg content_image/940627.jpg content_image/940628.jpg
<img src='content_image/940626.jpg'>

Herein R is as defined above. 

Examples of the sulfonium cation are shown below but not limited thereto. ’ 

<img src='content_image/940627.jpg'>

-continued 

<img src='content_image/940628.jpg'>

-continued 

