Reductive cleavage reaction of .gamma.-functionalized .alpha.,.beta.-unsaturated esters and halomethyls mediated with magnesium in methanol

Pak, Chwang Siek; Lee, Eun; Lee, Ge Hyeong

doi:10.1021/jo00058a038

Cited by 63 publications

(21 citation statements)

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“…In this direction, regioselective epoxidation of the C4–C5 olefin present in commercially available methyl sorbate ( 12a ) with m CPBA returned epoxy ester 13a in excellent yield, requiring no further purification 11. Reductive cleavage of 13a with magnesium in dry methanol afforded corresponding allylic alcohol 14a exclusively as the ( E )‐diastereomer, as evidenced from the characteristic coupling ( J = 15.6 Hz) between the vicinal olefinic proton resonances 12. When 14a was treated with a large excess amount of triethylorthoacetate (10 equiv.)…”

Section: Resultsmentioning

confidence: 99%

Identification of the First Alkenyl Chiloglottone Congener

2012

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Orchids of the genus Chiloglottis rely on sexual deception to attract a male thynnine wasp, whereupon a courtship routine results in the deposition and transfer of pollinia and subsequent pollination of the orchid. The chemical cues responsible for this behavior were recognized as a new class of natural products and efforts to synthetically prepare them, to assist in structural identification and to aid in ecological studies, have been ongoing. Most recently the first alkenylated member of this class was proposed based on GC–MS analysis of a physiologically active compound present in an orchid extract. The current work reveals synthetic efforts that provide access to diastereomerically pure unsaturated chiloglottone analogues and in combination with laboratory‐based electrophysiological assays and field‐based studies have unambiguously allowed identification of 5‐allyl‐2‐ethyl‐1,3‐cyclohexanedione (1d, chiloglottone 4) as the first alkenyl congener in the chiloglottone family. Convergent synthetic approaches, involving copper(I)‐mediated conjugate addition to a glutaconic ester converging on cadmium‐mediated desymmetrization of cyclic anhydrides or a Johnson–Claisen rearrangement of a mixed ketene acetal provided the appropriately substituted δ‐keto acids suitable for carbocyclization to furnish the required chiloglottone analogues.

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Section: Resultsmentioning

confidence: 99%

Identification of the First Alkenyl Chiloglottone Congener

2012

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“…The compounds 8 and 8 a were independently subjected to the desilylation reaction by treatment with n‐tetrabutylammonium fluoride to give the alcohols 25 and 25 a and were further treated independently with triphenylphosphine in presence of carbon tetrachloride and catalytic amount of sodium bicarbonate to furnish the corresponding chloro compounds 7 and 7 a respectively. The compounds 7 and 7 a were exposed to 6 eq.…”

Section: Resultsmentioning

confidence: 99%

Stereoselective Total Syntheses of (R )-Strongylodiols A, B, C and D

2017

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A facile stereoselective approach for the total syntheses of (R)strongylodiols A, B, C and D is described. A chiron approach has been followed wherein the stereochemistry at the chiral center is fixed and a methodology of base induced elimination of b-alkoxy chloride to get the chiral propargyl alcohol is employed. A key intermediate synthesized from commercially available (-)-diethyl D-tartrate has been utilized for the total syntheses of all the four titled compounds.

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“…9 A coupling reaction of aldehyde obtained by Swern oxidation of 4 and triphenyphosphorane afforded (-)-5 (41% for two steps). By simply applying the reductive cleavage reaction of α, β-unsaturated ester 5 by magnesium in methanol, 10 we obtained the sole product (-)-6 in 72% yield. The secondary hydroxyl group of 6 was protected by the TBDMSCl-DMAP-Et 3 N system in DMF to produce 7 in 80% yield.…”

Section: Resultsmentioning

confidence: 99%