Interpretation:

(1) Structures 1-6 are identical, but

displayed from different angles (but

would become different if there

were any substituents).

(2) Primed and unprimed structures

are related by a ring flip (e.g.,

1 and 1’).

(3) Interconversion is possible without

passing through a boat TS!

(4) The boat is destabilized because

of a van der Waals interaction

between the carbons rather than

the “flagpole” protons.

(5) There are substantial deviations

in the boat from tetrahedral angles;

thus, the hybridizations are

not sp3.

diagram: see ref on previous page

Sauers J Chem Ed 2000 77 332

Two Possible Pathways:

(A) chair, half-twist TS, twist intermediate, half twist TS’, chair’

(B) chair, half-twist TS, twist intermediate, boat TS, twist intermediate’,

half-twist TS’, chair’