Stereochemistry and Crystal Structures of Bis Cycloadducts of Danishefsky's Diene (Me3SiOC(=CH2)CH=CHOMe) with 2,5- and 2,6-Dichlorobenzoquinone

Syntheses and single crystal X-ray structural characterizations are reported for bis adducts (6) and (7) formed between Danishefsky's diene (8) with (respectively) the dienophiles 2,6- and 2,5-dichlorobenzoquinone. Formation of each adduct involves diastereocontrolled creation of six stereogenic centres.