天然产物Bryostatins北半部的合成研究

Bryostatins are a class of marine macrolides which feature three pyran moieties and eleven chiral centers. Bryostatins possess remarkable biological activities.The methods reported at present to construct the northern portion of Bryostatins have some drawbacks such as more steps, using expensive chemicals, difficulty in separation and purification.Herein, we describe the preliminary studies towards the new route of the construction of Bryostatins\' north part.First, we used intramolecular ene reaction between enol sily ether of ketone and alkyne to construct compound 5, after nucleophilic substitution, ozonolysis of double bond etc., we got compound 6 from commercially available starting material 9, thenwe employed Aldol reaction to assemble the key fragment 4 in moderate yield and 3:1 diastereoselectivity after condition screening, which laid the foundation for subsequent synthesis.