Scheme 1.
Sclerolog Synthesis via an Aldol-Cycloaldol Sequence.
a. 1. LDA, THF, −78 °C. 2. 2a–f. 3. HOAc. b. Ag2O, BrCH2CO2R, DMF, 2,6-lutidine, rt. c. 1. KHMDS, THF, −78 °C. 2. HOAc.
a 2a–d: 2-bromo-, 3-bromo-, 2,3-dichloro-, 2,4-dichlorobenzaldehyde, respectively; 2e: 1-naphthaldehyde; 2f : pyridine-2-carboxaldehyde.