Synthesis of the C29−C37 Bicyclic Ether Core of (+)-Sorangicin A

Abstract

Construction of the unique bicyclic bis-ether core of the macrolide (+)-sorangicin A has been achieved. This fragment was prepared by utilizing a one-pot cascade of three bond forming events. An epoxide opening of the epoxy tosylate 2 led to the formation of the tetrahydropyran and subsequently to a second epoxide. Finally, a second epoxide opening closed the tetrahydrofuran ring. The bicyclic fragment was synthesized in just nine steps from (E)-cinnamaldehyde.

Enantioselective synthesis of bicarbocyclic structures with an all-carbon quaternary stereocenter through sequential cross metathesis and intramolecular Rauhut–Currier reaction

“…In all cases, an excess of alkene was essential for maximizing the conversion of 2. 39 As has been previously reported 22 , the cross metathesis was amenable to a variety of alkenes (Table 1). Alkenes functionalized with a ketone, 1,3-dioxolane, ester, acid and sulfone were all successful, although the sulfone was markedly less efficient.…”

Stereoselective total synthesis of (+)-sapinofuranone B

“…The olefin 26 was subjected to cross metathesis with ethyl acrylate in presence of Grubbs' second generation catalyst to yield a,b-unsaturated ester 10. 17 Selective reduction of a,b-unsaturated double bond was achieved with NiCl 2 and NaBH 4 to yield product 27. 18 LiHMDS provided inseparable mixture of diastereomers 5 and 5a in 40:60 ratio.…”

“…The crude diastereomeric mixture was purified by silica gel (100e200 mesh) column chromatography using hexane/ethyl acetate as eluent to afford allylic alcohol 16 (11.7 g, 72%) as colorless liquid. R f (10% EtOAc/hexane): (17). To alcohol 16 (9.00 g, 28.5 mmol) in anhydrous CH 2 Cl 2 (120.0 mL) at 0 C were added N,N-diisopropylethylamine (29.7 mL, 170.8 mmol) and catalytic amount of DMAP and the mixture was stirred for 15 min.…”

Three‐Membered Heterocycles. Structure and Reactivity

“…411), the scope of which was described in detail by Sharpless in 1987 [447], is an almost indispensable tool for the synthetic chemist, as evidenced by its application in the construction of the bicyclic ether core of ( þ )-sorangicin A (i.e., 412 ! 413) reported by Crimmins and Haley [448].…”