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Schenk, Wolfdieter A.; Kümmel, Jörg; Reuther, Irene; Burzlaff, Nicolai; Wuzik, A.; Schupp, O.; Bringmann, Gerhard

doi:10.1002/(sici)1099-0682(199910)1999:10<1745::aid-ejic1745>3.3.co;2-t

Cited by 9 publications

(11 citation statements)

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“…The second crucial step requires the atroposelective transformation of the axially prostereogenic lactones 33 into configurationally stable biaryl compounds, which can be achieved simply by cleavage of the bridge with chiral O, N, or H nucleophiles (Scheme ) 20. 229, 230 Potassium ( S )‐1‐phenylethylamide (( S )‐ 259 ) and sodium ( R )‐menthoxide (( R )‐ 261 ) were the N and O nucleophiles of choice for the atropodiastereoselective ring opening of 33 b and 33 c , leading to the respective biaryl amides 258 and esters 260 in good yields (70–97 %) and diastereoselectivity (74–90 % de ) 231–233. Almost complete control of the configuration at the biaryl axis was attained in the atropodiastereoselective cleavage of 33 c with the sterically more demanding sodium ( R )‐8‐phenylmenthoxide (( R )‐ 262 ), delivering exclusively the ester ( M , R ) ‐ 263 c in 95 % yield 232…”

Section: Atroposelective Transformations Of Prostereogenic Biaryl mentioning

confidence: 99%

Atroposelective Synthesis of Axially Chiral Biaryl Compounds

et al. 2005

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A rotationally hindered and thus stereogenic biaryl axis is the structurally and stereochemically decisive element of a steadily growing number of natural products, chiral auxiliaries, and catalysts. Thus, it is not surprising that significant advances have been made in the asymmetric synthesis of axially chiral biaryl compounds over the past decade. In addition to the classic approach (direct stereoselective aryl-aryl coupling), innovative concepts have been developed in which the asymmetric information is introduced into a preformed, but achiral-that is, symmetric or configurationally labile-biaryl compound, or in which an aryl--C single bond is stereoselectively transformed into an axis. This Review classifies these strategies according to their underlying concepts and critically evaluates their scope and limitations with reference to selected model reactions and applications. Furthermore, the preconditions required for the existence of axial chirality in biaryl compounds are discussed.

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Section: Atroposelective Transformations Of Prostereogenic Biaryl mentioning

confidence: 99%

Atroposelective Synthesis of Axially Chiral Biaryl Compounds

et al. 2005

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“…As an example, F, which was easily prepared from the 'normal' (oxo)lactone F, was transformed in high yields (> 95% for all representatives D±I) into the chiral (cationic) ruthenium 6,6-CHIRAPHOS complex F, us- ing the thiophene ruthenium complex . 86 Reductive ring cleavage of F (here with LAH) gave 3-F, which, upon methylation and decomplexation, led to the thioether 3-F in an enantiomeric ratio of 88:12. The chiral ruthenium complex thus recovered can be converted back into the original complex in one step, without loss of stereochemical purity.…”

Section: Tpurrã !mentioning

confidence: 99%

“…The chiral ruthenium complex thus recovered can be converted back into the original complex in one step, without loss of stereochemical purity. 39,86,87 This ring cleavage with cheap, achiral reductants, combined with the possibility of recycling the chiral ruthenium reagent, constitutes an interesting novel alternative to the use of chiral hydride transfer reagents.…”

Section: Tpurrã !mentioning

confidence: 99%

The Lactone Concept: An Efficient Pathway to Axially Chiral Natural Products and Useful Reagents

1999

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$EVWUDFW A highly efficient concept for the stereoselective synthesis of axially chiral biaryl target molecules is presented: the atroposelective ring cleavage of configurationally unstable lactonebridged biaryls. The method has almost no restrictions concerning the substitution pattern, works even for substrates with high steric hindrance at the RUWKR-position(s) of the axis, and allows the optional, atropo-divergent preparation of each atropisomer from the same biaryl lactone precursor and a recycling of the undesired minor product in the sense of a chiral economy. A broad series of successful applications in natural product and ligand syntheses underlines the high value of the method. .H\ ZRUGV axial chirality, biaryl natural products, biaryl ligands and reagents, atropo-divergent synthesis, lactone-bridged biaryls '-BINAP' () R 7

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“…The solvent was removed under re duced pressure and the residue examined by NMR spec troscopy to show, besides the starting materials, (13). The sulfinic acid ester 13 was separated from the reaction mixture by extraction with diethylether (10 ml).…”

Section: Crossover Experiments Betw'een [Cpru(co)mentioning

confidence: 64%

Synthesis of Halfsandwich Ruthenium Complexes of Sulfinic Acid Esters [1]

Schenk

Kuhnerta

2000

Zeitschrift Für Naturforschung B

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A series of halfsandwich ruthenium sulfinato complexes [CpRu(PR'3)2(SO:R)] (R = Me, CH 2Ph, C2H4Ph, Ph, 4 -CöH4Me; PR'3 = PM e3, 1/2 dppm) with various electronic and steric environments around the ruthenium centre, have been prepared by insertion of SO2 into a ruthenium carbon bond, by a direct ligand exchange reaction, or by oxidation of thiolato complexes with 3-chloroperoxybenzoic acid. The chiral complexes [CpRu(C0 )(PPh3)(S0 2 R)] (R = Me, CH2Ph, Ph) were obtained similarly by oxidation of the corresponding thiolates with magnesium monoperoxyphthalate. Alkylation of the sulfinato complexes with oxonium salts [Rm 3 0 ]X (R" = Me, Et; X = B F 4 , PF6) gave ruthenium complexes of sulfinic acid esters, [C pRu(L)(L')(S(0)(0R ")R)]X in high yields and, for the chiral complexes, up to 82% de. The esters may be detached from the metal by ligand exchange with acetonitrile. Stronger nucleophiles such as I~ or SMe~ dealkylate the coordinated sulfinic acid esters.

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Cited by 9 publications

References 0 publications

Atroposelective Synthesis of Axially Chiral Biaryl Compounds

Atroposelective Synthesis of Axially Chiral Biaryl Compounds

The Lactone Concept: An Efficient Pathway to Axially Chiral Natural Products and Useful Reagents

Synthesis of Halfsandwich Ruthenium Complexes of Sulfinic Acid Esters [1]

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