Reactions of 3,4-Estrone Quinone with Mimics of Amino Acid Side Chains

Reaction of 3,4-estrone o-quinone (3,4-EQ) with several amino acid side chain mimics, including 4-ethylphenol, 4-methylimidazole, acetic acid, and propanethiol, gave a mixture of several products including the catechol, Michael addition products, and dimeric products of the catechol. On the other hand, several other amino acid side chain mimics, including ethanol, acetamide, 1-ethylguanidine, and 3-methylindole, did not result in any addition products or catechol formation. Michael addition to 3,4-EQ with 4-methylimidazole, acetate, and 4-ethyl phenoxide resulted in 1,4-addition, leading to C-1 adducts while reaction with propanethiol gave the C-2 addition product.