Stereoselective Synthesis of (+)-Boronolide

Cardá, Miguel; Rodrı́guez, Santiago; Segovia, Beatriz; Marco, J. Alberto

doi:10.1021/jo025813f

Cited by 53 publications

(10 citation statements)

References 13 publications

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“…It appeared that we required a protecting group on the side‐chain that could be removed under conditions that would circumvent cyclisation onto the C‐5 ketone. We therefore selected acetonide‐protected iodide 20 as our alternative side‐chain fragment, as oxidative cleavage of the acetonide33 would afford aldehyde 18 directly (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

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Synthesis of DOHNAA, a Mycobacterium tuberculosis Cholesterol CD Ring Catabolite and FadD3 Substrate

et al. 2015

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DOHNAA (2) is a key catabolite in the Mycobacterium tuberculosis (Mtb) cholesterol degradation pathway. The CoA ester of 2 has been implicated in regulation of gene transcription that is ultimately responsible for degradation of the C and D rings of cholesterol. A synthetic route to 2 is reported here, by a key DMSO‐mediated Morita–Bayliss–Hillman‐type alkylation of the Hajos–Parrish dione. As DOHNAA has to date only been available from microbial sources in very small quantities, the synthesis described will enable further studies of the enzymes involved in cholesterol degradation in Mtb and facilitate ongoing structure–activity studies based on this compound scaffold.

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Section: Resultsmentioning

confidence: 99%

“…Oxidation of alcohol 22 to the ketone with IBX in DMSO gave hexahydroindanedione 23 in high yield. The acetonide was transformed into aldehyde 18 by deprotection/oxidative cleavage using periodic acid in ethyl acetate in moderate yield 33. The final step to complete the synthesis of DOHNAA was a Pinnick oxidation.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of DOHNAA, a Mycobacterium tuberculosis Cholesterol CD Ring Catabolite and FadD3 Substrate

et al. 2015

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“…5,7 In the case of 5, a similar analysis leads to 2,6-dideoxy-L-xylohexose (L-boivinose), a monosaccharide which is not available commercially (Scheme 1). Several syntheses of this and related 2,6-dideoxyhexoses have been previously reported in the literature.…”

Section: Resultsmentioning

confidence: 99%

Stereoselective synthesis of the published structure of synargentolide A and of one stereoisomer thereof

Garcı́a-Fortanet¹,

Murga²,

Cardá³

et al. 2005

Arkivoc

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A stereoselective synthesis is described of the structure published for the naturally occurring synargentolide A, an α,β-unsaturated lactone. The key steps of the synthesis were a Brown´s asymmetric allylation and a ring closing metathesis. The spectroscopic data of the synthetic product were very close to those of the natural product but did not exactly match them. An epimer of the published structure was then synthesized according to a similar strategy. Again, the data of the synthetic product did not match those reported for the natural product. It is thus likely that the actual structure of synargentolide A differs from the published one in more than mere stereochemical aspects.

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“…bulkier R 1 -group occupies the outer position of the ring antiperiplanar to the bond being formed, while the α-Me group is oriented away from the metal, to explain the observed selectivity [27]. The robustness of this chemistry can be seen in the total synthesis of zincophorin (46) by Cossy and coworkers [28] and studies toward the total synthesis of saliniketal A (50) by L.C. Dias and C.C.…”

Section: 4-asymmetric Induction Using α-Methyl-β-branched Ketonesmentioning

confidence: 97%

“…This chemistry was applied in the total synthesis of (+)-boronolide (103) [46]. In these studies, the authors observed that addition of the boron enolate generated from methyl ketone 104 to aldehyde 105 produced aldol adduct 106, which has a 1,5-anti relationship between the β-alkoxy group and the newly formed stereogenic center.…”

Section: 4-asymmetric Induction Using α-Alkoxy Ketonesmentioning

confidence: 99%

Asymmetric Induction in Aldol Additions

Dias¹,

Polo²,

Lucca³

et al. 2013

Modern Methods in Stereoselective Aldol Reactions

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The selectivity of aldol reactions involving kinetic enolates is related to various factors such as the nature of the Lewis acid (Li, Mg, B, Al, Ti, Sn, etc.), the presence of stereogenic centers in both the substrates and reagents, the nature of their substituents and the reaction conditions. Another factor of major importance is the nature of the enolate double bond (Z or E) [1].In general, it is well known that in aldol reactions involving metal enolates, which proceed through a six-membered cyclic transition state, the Z-enolate leads to the formation of 1,2-syn aldol adducts and the E-enolate affords aldol adducts with the 1,2-anti configuration. A rationalization for the observed selectivities of these aldol reactions was proposed by Zimmerman and Traxler (Scheme 5.1) [2]. According to this model, the nature of the double bond geometry plays a primary role in determining the energies of the competing transition states. For Z-enolates, the transition state TS2 is more destabilized than transition state TS1 because of the 1,3-diaxial interactions between the R 1 and R 3 substituents as well as between these substituents and one of the metal ligands (L). Therefore, the Z-enolate preferentially leads to the formation of the 1,2-syn aldol adduct.For the E-enolate, 1,3-diaxial interactions between the R 1 and R 3 substituents and between both R 1 and R 3 and one of the metal ligands are present in transition state TS4. Therefore, the 1,2-anti aldol adduct is obtained from the lower energy transition state TS3.Modern aldol reactions use preformed enolates to obtain good yields by preventing side reactions. This methodology has proven to be very effective for various Lewis acids derived from lithium, titanium, tin, and boron. By using preformed enolates with chiral substrates and reagents, it is possible to obtain aldol adducts with an excellent degree of asymmetric induction.The IUPAC defines asymmetric induction as the traditional term describing the preferential formation in a chemical reaction of one enantiomer (or diastereomer) over the other as a result of a chiral feature present in the substrate, reagent, catalyst, or the environment [3].

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Stereoselective Synthesis of (+)-Boronolide

Cited by 53 publications

References 13 publications

Synthesis of DOHNAA, a Mycobacterium tuberculosis Cholesterol CD Ring Catabolite and FadD3 Substrate

Synthesis of DOHNAA, a Mycobacterium tuberculosis Cholesterol CD Ring Catabolite and FadD3 Substrate

Stereoselective synthesis of the published structure of synargentolide A and of one stereoisomer thereof

Asymmetric Induction in Aldol Additions

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