ChemInform Abstract: Condensed Cyclic and Bridged‐Ring System: Part 16. Synthesis of Diastereoisomeric (6SR, 10SR)‐10‐Hydroxy‐2‐methoxy‐6‐methyl‐6,10‐ methano‐5‐oxo‐6,7,8,9,10,11‐hexahydro‐5H‐benzocyclononen‐12‐ylacetic Acid Lactones.

Abstract

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A One Pot Synthesis of Dehydrohedione (DHH) from a Hedione® Precursor

“…A much cleaner reaction was observed when 3a was decarbomethoxylated in the presence of equimolar H 2 O in NMP at 155 °C, (61% yield). Under basic conditions (Li 2 CO 3 , py, 100 °C), 3a afforded quantitatively 4b as a 9:1 mixture of stereoisomers, via cyclopropanation and LiCl mediated Krapcho decarbomethoxylation . When treated with CuCl (2.0 mol‐equiv., MeOH, 65°, 18 h), 8a remained unchanged, while under the same conditions with CuCl 2 , the reaction was very sluggish, and only 10% conversion towards DHH 1a was observed.…”

“…to large excess) at 20 – 60 °C did not afford 1a . It is noteworthy that the Krapcho demethoxycarbonylation is usually performed in a polar aprotic solvent . For non‐exhaustive examples of Cu 2+ decarboxylation, see, for some examples where Cu + is involved, see …”