Total synthesis of 11-deoxydaunomycinone and analogs by a tandem Claisen-Diels-Alder strategy
Woo, Soon Hyung
11-Deoxydaunomycinone (6), ita 4-deoxy analogue 5, and 1-methoxy-4,ll-dideoxyduanomycinone were prepared by a sequence involving an intramolecular acyl transfer reaction followed by a tandem Claisen-Diels-Alder reaction. The resulting diketone could be oxidized to naphthoquinone 11 with DDQ. This quinone was then treated with either 1-[ (trimethylsilyl)oxy]butadiene or l-methoxy-1,3-cyclohexadiene to provide adducts that could be transformed into 5 and 6. Unfortunately, the presence of the C-7 carbonyl group decreased the regioselectivity of 11 in Diels-Alder reactions.
Reprinted (adapted) with permission from The Journal of Organic Chemistry,52(22); 4841-4846. Doi: 10.1021/jo00231a003. Copyright 1987 American Chemical Society.