A convergent stereocontrolled total synthesis of (−)-terpestacin

Abstract

A stereocontrolled total synthesis of (-)-terpestacin has been achieved starting from (R)-(-)-carvone as a chiral pool and (E,E)-farnesol via a highly convergent approach. Thus, (R)-(-)-carvone was transformed into the cyclopentanone segment through a series of high yielding operations with the proper setup of all the stereochemical centers while (E,E)-farnesol was converted into the other requisite building block via a series of high yielding reactions. The cyclopentanone intermediate was both selectively enolized and alkylated at room temperature to yield the desired coupling product, which provided the natural product upon further transformations.

Short, Enantioselective Total Synthesis of Highly Oxidized Taxanes

“…The net conversion of enone 17 into the trans ‐diol 22 proved to be an incredibly challenging undertaking with a surprisingly simple solution. First, subjection of 17 to Et 2 NLi followed by the Vedejs reagent (MoOPh) delivered the α‐hydroxy enone 18 , which was directly exposed to Cu(OAc) 2 to form the dione 19 in 77 % yield (along with 12 % recovered enone 17 ). The unusual aluminum‐based reducing agent LiAlH(O t Bu) s Bu 2 (2.5 equiv) was then employed to stereo‐ and siteselectively produce 20 .…”

Synthesis of Chiral Cyclopentenones

“…Selection of synthetic bioactive and natural molecules containing a chiral cyclopentenone functionality, such as prostaglandins and prostanoid derivatives, pentenomycins, lathyranoic acid A, , untenone A, , sesquiterpene from Acorus calamus rhizomes, daphmacromines, kjellmanianone, litseaverticillols, terpestacin, , przewalskin B, azadiradione, minwanenone, jiadifenin, , rupestonic acid, (+)-achalensolide, guaiane, parthenin, didemnenones, , lanostanoid from Antrodia camphorate, hookerolides A–D, 4α-phorbol-12,13-didecanoate, lobocrasol, gochnatiolides A–C, ainsliadimer-B, 4α-4-deoxyphorbol, and guaiane glycosides …”

Metallacycle-mediated cross-coupling in natural product synthesis

“…101–107 In 2003, Jamison reported an enantioselective synthesis of this natural product that featured two different metallacycle-mediated coupling reactions: (1) an early example of metallacycle-mediated alkyne–aldehyde coupling in natural product synthesis, and (2) an intermolecular Pauson–Khand annulation (a special type of metallacycle-mediated alkyne–alkene coupling that will be discussed later in this Report). 108, 109 As illustrated in Figure 25B, Ni-catalyzed coupling of alkyne 58 to aldehyde 59 delivered the desired product 60 in 41% isolated yield, yet proceeded with only moderate levels of selectivity (rs = 2.6:1, ds = 2:1).…”