Studies on Azulenes. IX. 3-(1-Hydroxyethyl)-S-guaiazulene.

3-(1-Hydroxyethyl)-S-guaiazulene (III) was prepared by reduction of 3-acetyl-S-guaiazulene (II) with lithium aluminum hydride. (III) was converted into 3-vinyl-S-guaiazulene (IV) by dehydration and further into 3-ethyl-S-guaiazulene (V) by catalytic hydrogenation. An isomeric carbinol (VIII) was also produced from S-guaiazulene-3-carboxaldehyde (VI) by its treatment with methylmagnesium iodide, and (VIII) was confirmed to be 3-(1-hydroxyethyl-S-guaiazulene by its derivation to (V). The remarkably different stability against dehydration observed between the two isomeric 3-(1-hydroxyethyl)-S-guaiazulenes (III and VIII) is discussed from the structural point of view.