Two principal modern methods for enantioselective aldol reactions — the Evans aldol and the Masamune aldol — use a carboxylic-acid derived enolate rather than a ketone enolate as e.g. in the Paterson aldol reaction. For ‘traditional’ ketone enolates, a rule of thumb dictates that (E) enolates giv...

I may be only a physicist but I'm familiar with the superscripted dot to indicate a radical. In a paper I'm reading the authors have also used a superscripted open circle. I can't find any reference online or in my physical chemistry textbook (Atkins). Here's an example: As you can see they'...