A model synthetic approach to synthesis of the pyridine C ring of the antitumor agent and antibiotic streptonigrin (1) is described. A hetero-Diels-Alder reaction is used as the method of ring construction. Studies of the reaction of dienophile 6 with dienes 13-16 and 18 are described in detail, particularly in regard to regioselectivity. A mechanistic model is proposed to rationalize the results. Adduct 27 has been converted to an acetylpyridine 42, which possesses four of the five substituents present in the desired streptonigrin synthon 3.
All Science Journal Classification (ASJC) codes
- Organic Chemistry