By using complementary and selectively acting reagents (TiCl4 and sulfurane 16), azafrin, the main carotenoid in the rhizomes of Escobedia scabrifolia, has been shown to have the (5 R:6 R)-configuration. Reaction of azafrinaldehyde ( 4) with (Ph3P)3RhCl leads to a mixture of 5 and 6, the latter arising probably through elimination of acetylene and recarbonylation.