; The oxazolidinone ring is a shallow envelope
conformation with the tert-butyl and iso-butyl groups
occupying trans-positions with respect to the ring. The
angles at the N atom sum to 356.2\%, indicating a very
small degree of pyramidalization at this atom. This is
consistent with electron delocalization between the N
atom and the carbonyl centre [N-C=O = 1.374(3)\%A].