Abstract:
Ketenimine is a synthetic intermediate that has been applied in wide ranges of
reactions. Cu(I) catalyzed cycloaddition reaction of alkyne with sulfonylazide is
reported to form ketenimine intermediate which participate in addition reactions with
various external nucleophiles e.g. amine, alcohol, water, etc. In the present work, we
demonstrate new types of reactions i.e. rearrangements of ketenimines involving a
flanking amino group as an internal nucleophile. We report that propargylamine
derivatives when reacted with sulfonylazides undergo a 1,3-amino group migration
leading to acrylamidines. The methodology allows the formation of acrylamidines
even in the presence of competing nucleophiles, such as H2O, alcohol, amine and
thiol. We further demonstrate that a flanked amino group also undergoes 1,5-
migration when a C=C moiety is introduced between the alkyne and the
aminomethylene group. Cis-stereochemistry of these groups around the C=C is
important for the rearrangement to proceed.
