Simultaneous Synthesis of Vitamins D(2), D(4), D(5), D(6), and D(7) from Commercially Available Phytosterol, β-Sitosterol, and Identification of Each Vitamin D by HSQC NMR

We succeeded in simultaneously synthesizing the vitamin D family, vitamins D(2), D(4), D(5), D(6), and D(7), from β-sitosterol, which is sold as a commercially available reagent from Tokyo Chemical Industry Co., Ltd. It is officially sold as a mixture of four phytosterols {β-sitosterol (40–45%), campesterol (20–30%), stigmasterol, and brassicasterol}. Owing to this, we anticipated that, using this reagent, various vitamin D analogs could be synthesized simultaneously. We also synthesized vitamin D(3) from pure cholesterol and analyzed and compared all vitamin D analogs (D(2), D(3), D(4), D(5), D(6), and D(7)) by HSQC NMR. We succeeded in clearly demonstrating the difference in the NMR chemical shifts for each vitamin D analog.