A new route to selectively protected cis 4a-methyl-hexahydronaphthalene-1(2H), 7(8H)-diones

Solid-Phase Synthesis of a Combinatorial Array of 1,3-Bis(acylamino)-2-butanones, Inhibitors of the Cysteine Proteases Cathepsins K and L

“…Therefore, the oxonium ion that is formed as an intermediate from the ketal is more subject to epimerization than the ketone using the reaction conditions typically employed to cleave amides from BAL resin. Attempts to further optimize the process by identifying reaction conditions that cleave amides from BAL resin and also hydrolyze dimethyl ketals while maintaining chiral integrity 26 were not made.…”

“…Past literature indicates that conditions might be found which reduce or eliminate this problem. 26 Alternate resin linkers with different cleavage conditions might resolve this problem, also. The most apparent solution, however, is a strategy where the resin linker and the ketone protective group are one, thus ensuring that the reaction conditions will be optimal for reduced epimerization while still producing resin cleavage.…”

“…Problems with epimerizations were identified that somewhat limit the utility of this methodology. Past literature indicates that conditions might be found which reduce or eliminate this problem . Alternate resin linkers with different cleavage conditions might resolve this problem, also.…”