paeonilactone A synthesis

Yield:-

Steps:

Multi-step reaction with 10 steps
1: 1.)9-borabicyclo<3,3,1>nonane 2.)hydrogen peroxide, NaOH / 1.) hexane
2: 75 percent / CrO₃, H₂SO₄ / acetone
3: 89 percent / diethyl ether
4: 73 percent / t-butyl chromate, Ac₂O / acetic acid; CCl₄ / Heating
5: 53 percent / NaBH(OCH₃)3 / diethyl ether / Heating
6: 89 percent / K₂CO₃ / methanol; H₂O
7: 1.)Amberlyst-15 2.) I₂ / 1.) CH₃CN 2.) 20 h, room temp.
8: 94 percent / tributyltin hydride, azobisizobutyronitrile / benzene / Heating
9: H₂SO₄ / methanol; H₂O / Heating
10: 60 percent / dimethyl sulfoxide; oxalyl chloride; (Et)3N / -50 °C

References:

Kadota;Takeshita;Makino;Kikuchi [Chemical and Pharmaceutical Bulletin,1989,vol. 37,# 3,p. 843 - 845]