Question

How do we get this numbering, in other meaning how is the numbering of carbon atoms?

Allenoate-Claisen Rearrangement NZ Lewis acid (LA) COR COR (LA) (3,3) LAO OOO CEC 0 0 H RO H addition across H (E)-enamine favored chair favored

Answer 1

Answer: By convention, we start numbering the carbon atom in chair conformation from bottom right corner (if it is flip conformation as in your case). So we will start numbering from bottom right corner. Then we found that in chair conformation on your molecule on the position 3 there is two substituent present i.e. Z and Z and to represent the position of Z in chair conformation of molecule we write as (3,3). This will show the position of that particular substituent as like Z in the chair conformation of your molecule. If one substituent is present it can be represented by single number such as (3) i.e. the position on which single substituent is present in chair conformation of the molecule.

And for your understanding I am drawing here your molecule and then will show how it is numbered in chair conformation and since your molecule is in flip conformation we will start numbering from bottom right corner as follows:

- LAO H 1 coolson 2 cazov)