Natural products Hajos-Wiechert reaction

The total synthesis of enantiopure natural products has been one of the key developments of the modem era of asymmetric synthesis. Since the Hajos-Wiechert reaction allows ready access to useful chiral bicyclic building blocks, the reaction has been widely employed to constmct a variety of precursors for the synthesis of steroids, vitamin D derivatives, and other natural products. The remainder of the review will look at select examples from the total synthesis literature to illustrate this point. 

The cephalostatins are a group of cytotoxic dimeric steroid derivatives from the marine worm Cephalodiscus gilchristi. Tietze and Krahnert prepared a group of natural product analogs using multiple Heck reactions using derivative 106 obtained from the Hajos-Wiechert reaction their approach is outlined below. ... 

Lastly, the figure below lists a number of other natural products for which Hajos-Parrish ketone and other derivatives from the Hajos-Wiechert reaction were employed as chiral building blocks to achieve partial or complete total synAeses. 

Another key event in the history of organocatalytic reaction was the discovery of efficient r-proline-mediated asymmetric Robinson annulation reported during the early 1970s. The so-called Hajos-Parrish-Eder-Sauer-Wiechert reaction (an intramolecular aldol reaction) allowed access to some of the key intermediates for the synthesis of natural products (Scheme 1.4) [37, 38], and offered a practical and enantioselective route to the Wieland-Miescher ketone [39]. It is pertinent to note, that this chemistry is rooted in the early studies of Langenbeck and in the extensive investigations work of Stork and co-workers on enamine chemistry... 

Hoffman-La Roche in the USA [28]. The so-called Hajos-Parrish-Eder-Sauer-Wiechert reaction provided access to key intermediates for the synthesis of natural products and offered a practical route to the Wieland-Miescher ketone (Equation 10.12). 

Scheme 1.14 Application of the Hajos-Parrish-Eder-Sauer-Wiechert reaction to natural product...

---