O'Brien EM, Li J, Carroll PJ, Kozlowski MC. Synthesis of the cores of hypocrellin and shiraiachrome: diastereoselective 1,8-diketone aldol cyclization.
J Org Chem 2010;
75:69-73. [PMID:
19894740 DOI:
10.1021/jo9018914]
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Abstract
Intramolecular 1,8-diketone aldol reactions were studied as a tool for the construction of the seven-membered rings of hypocrellin and shiraiachrome. Conditions were identified to obtain the relative stereochemistries present in the two natural products with excellent diastereoselectivity. In addition, a nine-membered ring congener, which has yet to be observed in nature, formed with high selectivity when a hindered amine was used in conjunction with silazide bases.
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