729. The synthesis of DL-baikiain

Total Synthesis of (±)‐Phomoidride D

“…Deprotonation of 13 at the terminal alkyne allowed selective reduction to the enyne 14 . Subsequent hydroalumination/iodination of 14 delivered the vinyl iodide 15 , which, after conversion into the corresponding cuprate was advanced by conjugate addition to the known α,β‐unsaturated ketone 12 . Under the illustrated TMSCl‐accelerated conditions, this latter reaction furnishes an intermediate silyl enol ether which, upon in situ exposure to N ‐bromosuccinimide (NBS), delivers 16 .…”

Synthesis of cyclic amino acid baikiain via asymmetric phase transfer catalysis

“…Because of the potential of 1 as a starting material for the preparation of diverse natural and non-natural compounds, the interest in synthesizing this compound is reflected in a number of published synthetic routes for both the enantiopure and racemic forms. An earlier synthesis of baikiain includes the racemic synthesis reported by Raphael [20], Burgstahler [21], and Herdeis [22]. More recently, Najera reported an enantioselective synthesis using the asymmetric alkylation of Seebach imidazolidinones [23] to obtain 1 in 24.5% overall yield and 90% e.e.…”

Total Synthesis of (±)‐Phomoidride D

“…[3a] In contrast to the latter efforts,our strategy employs aregioisomeric b-ketoester that derives from the ketone 5,w hich was seen as arising from Whartonf ragmentation of the isotwistane 6.A lthough increasing structural complexity in ar etrosynthesis appears counterintuitive from as trategic planning perspective,w e envisioned accessing 6 by aketyl-initiated cascade cyclization wherein an exo-methylene lactone serves as al ynchpin and bromide as the nucleofuge.The cyclization cascade precursor (7)w ould arise from the [2.2.2] bicycle 8,t he product of at andem phenolic oxidation/inverse-electron-demand intramolecular Diels-Alder (IMDA) cycloaddition, wherein the phenol 9 serves as asubstrate.T his highly efficient combination of two cascade reactions allows global control of the relative stereochemistry and introduces all but five carbon centers present in 4.The phenol 9 would arise from the readily available precursors 10, 11,a nd 12. Deprotonation of 13 at the terminal alkyne allowed selective reduction to the enyne 14.S ubsequent hydroalumination/iodination of 14 delivered the vinyl iodide 15, [10] which, after conversion into the corresponding cuprate was advanced by conjugate addition to the known a,bunsaturated ketone 12. Deprotonation of 13 at the terminal alkyne allowed selective reduction to the enyne 14.S ubsequent hydroalumination/iodination of 14 delivered the vinyl iodide 15, [10] which, after conversion into the corresponding cuprate was advanced by conjugate addition to the known a,bunsaturated ketone 12.…”