Yield:-

Steps:

Multi-step reaction with 8 steps
1: 88 percent / triethylamine / dimethylformamide / 24 h / 95 °C
2: 96 percent / TiCl₄ / CH₂Cl₂ / 1.5 h / -78 °C
3: 90 percent / p-toluenesulfonic acid / benzene / 2 h / Heating
4: 81 percent / TiCl₄ / CH₂Cl₂
5: 71 percent / NaNH₂ / benzene
6: 1.) O₃; 2.) Zn/CH₃COOH / 1.) -78 deg C, 30 min; 2.) room temperature overnight.
7: 73 percent / HCl / acetic acid / 21 h / Ambient temperature
8: Al₂O₃ / hexane / 24 h / 60 °C

References:

Yanami, Tetsuji;Miyashita, Masaaki;Yoshikoshi, Akira [Journal of Organic Chemistry,1980,vol. 45,# 4,p. 607 - 612]