参考文献：[1] Patent: WO2004/14879, 2004, A1. Location in patent: Page 13-14
路线2：
参考文献：[1] Journal of Antibiotics, 1999, vol. 52, #7, p. 674-676；[2] Bioorganic and Medicinal Chemistry Letters, 2013, vol. 23, #11, p. 3253-3256；[3] Bioorganic and Medicinal Chemistry Letters, 2008, vol. 18, #9, p. 2886-2890；[4] Organic Process Research and Development, 2005, vol. 9, #2, p. 179-184
路线3：
参考文献：[1] Patent: US2011/224129, 2011, A1；[2] Organic Process Research and Development, 2005, vol. 9, #2, p. 179-184
