Natural product synthesis Yohimbine

The new protocol was applied in the synthesis of (-l-)-yohimbenone from (-1-)-yohimbine and other natural products such as (-l-)-sclareolide, a deoxychohc acid... 

The final natural product that will be discussed herein to demonstrate the applicability of asymmetric organocatalysis to assemble the monoterpenoid part of indole alkaloids is (H-)-yohimbine (282) (Scheme 6.46). Yohimbine is a well-known monoterpenoid indole alkaloid that has been isolated from several natural sources and for which the first total synthesis dates back to the 1950s [140]. Two organocatalytic total syntheses of this important natural product have been reported recently by the groups of Jacobsen and Hiemstra [141,142], Jacobsen s synthesis of 282 commenced with the thiourea 170a-catalyzed acyl-Pictet-Spengler reaction between tryptamine 283 and the protected hydroxyaldehyde... 

This chapter will address developments in yohimbine synthesis of the past 10-12 years. A number of reviews have already been published in this area (3-15). Additionally, the spectroscopic properties of these alkaloids have also been investigated (16-18) although a discussion is beyond the scope of this chapter. Unlike other reviews in this field, this report will focus exclusively on the approaches designed to tackle the synthetic challenges presented by the yohimbine alkaloids and will be organized by the methodologies actually used rather than by the specific natural product targets. 

---