Total synthesis of ionophore antibiotic X-14547A

Nicolaou, K. C.; Papahatjis, Demetris P.; Claremon, David A.; Magolda, R. L.; Dolle, Roland E.

doi:10.1021/jo00209a017

Cited by 104 publications

(37 citation statements)

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“…7 Reaction of epoxide 5 with excess magnesium 4-methoxyphenyl cuprate followed by standard Swern oxidation 8 furnished the (R)-ketone 7 in essentially quantitative yield. Reduction of 7 with NaBH 4 generated an inseparable mixture of syn/anti 6 in quantitative yield with 9∶1 diastereoselectivity as revealed by 1 H NMR.…”

Section: Resultsmentioning

confidence: 99%

“…Herein, we describe a facile simple route to total synthesis of (＋)-di-O-methyl nyasol (3b), (＋)-tetrahydronysol (4), together with those of ( -)-di-O-methylagatharesinol (lb) and (-)-di-O-methylsugiresinol (2b) from (S,S)-1,4-bis(benzyloxy)-2,3-epoxybutane (5). 7 The absolute configuration of (＋)-3a was confirmed via first total synthesis of (＋)-3b and (＋)-4.…”

Section: Introductionmentioning

confidence: 99%

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A Facile Approach to Synthesis of the Di‐O‐methyl Ethers of (−)‐Agatharesinol, (−)‐Sugiresinol, (+)‐Nyasol and (+)‐Tetrahydronyasol

Quan

Zhang

et al. 2007

Chin. J. Chem.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Facile Approach to Synthesis of the Di‐O‐methyl Ethers of (−)‐Agatharesinol, (−)‐Sugiresinol, (+)‐Nyasol and (+)‐Tetrahydronyasol

Quan

Zhang

et al. 2007

Chin. J. Chem.

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“…As a way to revalorize glycerol, our group has adopted new approaches based on the transformation of this polyol into halohydrin esters [11][12][13]. These products can be used as building blocks for the synthesis of a range of biologically active natural and synthetic products [14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

From Symmetric Glycerol Derivatives to Dissymmetric Chlorohydrins

Solarte¹,

Escribà²,

Eras³

et al. 2011

Molecules

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Abstract:The anticipated worldwide increase in biodiesel production will result in an accumulation of glycerol for which there are insufficient conventional uses. The surplus of this by-product has increased rapidly during the last decade, prompting a search for new glycerol applications. We describe here the synthesis of dissymmetric chlorohydrin esters from symmetric 1,3-dichloro-2-propyl esters obtained from glycerol. We studied the influence of two solvents: 1,4-dioxane and 1-butanol and two bases: sodium carbonate and 1-butylimidazole, on the synthesis of dissymmetric chlorohydrin esters. In addition, we studied the influence of other bases (potassium and lithium carbonates) in the reaction using 1,4-dioxane as the solvent. The highest yield was obtained using 1,4-dioxane and sodium carbonate.

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“…Stereochemistry of the aldol adduct 4c was determined by transforming to the known compound 6. 31) After protection of the secondary alcohol with TBSOTf, the chiral auxiliary group was reductively removed with NaBH 4 to provide the alcohol 5. Ozonolysis of 5, reduction of the resulting aldehyde, followed by acetal formation gave the known compound 6.…”

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confidence: 99%

Stereoselective Vinylogous Mukaiyama Aldol Reaction of .ALPHA.-Haloenals

Iwasaki

Matsui

Suzuki

et al. 2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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We previously reported a highly stereoselective vinylogous Mukaiyama aldol reaction (VMAR) using vinylketene silyl N,O-acetal 1 and 2, which provides a unique and remarkable entry to a remote asymmetric induction (Chart 1).1-3) From a synthetic point of view, this method can directly afford the anti-d-hydroxy-a,g-dimethyl-a,b-unsaturated carbonyl unit which is seen in many naturally occurring products. Indeed, VMAR has successfully been utilized in natural product syntheses by many groups [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] including ourselves. [21][22][23][24][25] However, a,b-unsaturated aldehyde is not generally a good substrate for VMAR in terms of yield (i.e., low to moderate). High yield could be achieved by the addition of a catalytic amount of water, 3) or by carrying out the reaction for a prolonged period of time. 5,11) In this context, we became interested in the employment of a-haloenals as substrates which are considered to be much more reactive compared to simple enals. We also reasoned that the VMAR products from ahaloenals could serve as versatile intermediates for introducing a variety of substituents using well-established Pd-mediated methodologies. Herein, we report a high-yielding and stereoselective VMAR of a-haloenals achieved under standard conditions (TiCl 4 in CH 2 Cl 2 , 2.0 eq of aldehyde). Some transformations of VMAR products from a-haloenals by Pdcatalyzed cross-coupling are also described.In this study, we examined VMAR of a-iodoenal 3a, 26) abromoenal 3b, 27) and a-chloroenal 3c 28,29) (Table 1). According to the established protocol, VMAR of a-iodoenal 3a (2.0 eq) with the vinylketene silyl N,O-acetal 2 using TiCl 4 (1.0 eq) afforded the corresponding anti-aldol adduct 4a in excellent yield with high diastereoselectivity (entry 1). In addition, VMAR of a-bromoenal 3b and a-chloroenal 3c also provided anti-adducts 4b and 4c 30) in excellent yield, respectively (entries 2, 3). Notably, a-halo substituents improved the yields of aldol adducts and shortened the reaction time compared with VMAR of tiglic aldehyde 3d (entry 4). Independently, Hosokawa and Tatsuta et al. reported that the VMAR of ent-2 and tiglic aldehyde 3d afforded ent-4d in good yield (82%) over a prolonged reaction time (4 d) at low temperature (Ϫ60°C). 5,11)Stereochemical determination of the aldol adducts 4a and 4b were easily achieved by Stille cross-coupling using a catalytic amount of Pd(dba) 2 and Me 4 Sn to convert the antiadduct 4d (Chart 2). The spectroscopic data of synthetic 4d We have developed a high-yielding and stereoselective vinylogous Mukaiyama aldol reaction (VMAR) of a ahaloenals. Contrary to the simple a a,b b-unsaturated aldehyde, a a-haloenals were found to be reactive affording the corresponding VMAR adducts in excellent yields. Some transformations of VMAR adducts by Pd-mediated cross-coupling were also examined in order to demonstrate the synthetic utility of VMAR of a a-haloenals.

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Total synthesis of ionophore antibiotic X-14547A

Cited by 104 publications

References 0 publications

A Facile Approach to Synthesis of the Di‐O‐methyl Ethers of (−)‐Agatharesinol, (−)‐Sugiresinol, (+)‐Nyasol and (+)‐Tetrahydronyasol

A Facile Approach to Synthesis of the Di‐O‐methyl Ethers of (−)‐Agatharesinol, (−)‐Sugiresinol, (+)‐Nyasol and (+)‐Tetrahydronyasol

From Symmetric Glycerol Derivatives to Dissymmetric Chlorohydrins

Stereoselective Vinylogous Mukaiyama Aldol Reaction of .ALPHA.-Haloenals

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