5,5-Dimethyl-1,4,2-dioxazoles as versatile aprotic hydroxamic acid protecting groups.
5,5-Dimethyl-1,4,2-dioxazoles are readily installed by transketalization of 2,2-diethoxypropane, where both the NH and OH moieties are protected in a nonprotic form. The dioxazoles are stable to a wide variety of reaction conditions and readily revert back to the hydroxamic acid by treatment with Nafion-H in 2-propanol. The method is applicable to primary, secondary, tertiary, and aromatic hydroxamic acids, and the acidity of the protons adjacent to the dioxazole allows alpha-functionalization.
Couturier
Michel
M
Process Research and Development, Pfizer Global Research and Development, Eastern Point Road, P.O. Box 8013, Groton, Connecticut 06340-8013, USA. michael_a_couturier@groton.pfizer.com
Tucker
John L
JL
Proulx
Caroline
C
Boucher
Ghislain
G
Dubé
Pascal
P
Andresen
Brian M
BM
Ghosh
Arun
A