摘要 |
Compounds and a method of synthesis of compounds of formula (Ia) or (Ib): and salts, solvates, and chemically protected forms thereof, wherein the dotted lines indicate the optional presence of a double bond between C1 and C2 or C2 and C3; R<SUP>2 </SUP>and R<SUP>3 </SUP>are independently selected from -H, -O, -CH<SUB>2</SUB>, -CN, -R, OR, halo, -CH-R, O-SO<SUB>2</SUB>-R, CO<SUB>2</SUB>R and COR; R<SUP>10 </SUP>is a carbamate-based nitrogen protecting group; and R<SUP>11 </SUP>is an oxygen protecting group.
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