O-Silylated steroidal cis-aminoalcohols as chiral auxiliaries: highly diastereoselective Pd-catalyzed cyclopropanation of α,β-unsaturated aldimines

Dubs, M.; Dieks, Henrik; Günther, Wolfgang; Kötteritzsch, Manuela; Poppitz, Wolfgang; Schönecker, Bruno

doi:10.1016/s0040-4039(02)00334-9

Cited by 19 publications

(7 citation statements)

References 23 publications

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“…The solvent was then evaporated to leave a yellow oil. The 3a-AMPY compound 25 was obtained as white crystals (2 Tetrakis(acetonitrile)copper(i) hexafluorophosphate (1.2 equiv) was added to a solution of 1 equivalent of the IMPY (3, 6, 12) or AMPY ligand (16,21,25) in absolute acetone that had been degassed with argon. The resulting brown solutions were stirred at room temperature.…”

Section: Methodsmentioning

confidence: 99%

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Intramolecular γ‐Hydroxylations of Nonactivated CH Bonds with Copper Complexes and Molecular Oxygen

Schönecker

Zheldakova

Lange

et al. 2004

Chemistry A European J

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Copper(I) complexes incorporating the isomeric bidentate ligands IMPY (iminomethyl-2-pyridines) or AMPY (aminomethylene-2-pyridines) are quite unusual in their ability to bind and activate molecular oxygen. Using these complexes, hydroxylations of nonactivated CH, CH2, or CH3 groups in the gamma-position in relation to the imino-nitrogen atom, and with a specific orientation of one H atom with respect to the binuclear Cu-O species, can be achieved in synthetically useful yields. Through mechanistic studies employing conformationally well-defined molecules (for example, cyclic isoprenoids), coupled with solid-state X-ray structure analyses and force-field calculations, we postulate a seven-membered transition state for this reaction in which six atoms lie approximately in a plane. This plane is defined by the positions of the lone pairs on the nitrogen atoms, as well as the copper and the oxygen atoms. For a successful hydroxylation, one hydrogen atom should be located close to this plane. Prediction of the stereochemical course of these reactions is possible based on a simple geometrical criterion. The convenient introduction of IMPY and AMPY groups as auxiliaries into oxo and primary amino compounds and the simple hydrolysis after the hydroxylation procedure has allowed the synthesis of 3-hydroxy-1-oxo and 3-hydroxy-1-amino compounds. If desired, the 3-hydroxy-1-IMPY and -1-AMPY compounds can be reduced with NaBH4 to obtain 3-hydroxy-1-aminomethylpyridines. For a successful hydroxylation procedure, the method employed for the synthesis of the CuI complexes is very important. Starting either from CuI salts or from CuII salts with a subsequent reduction with benzoin/triethylamine may turn out to be the better way, depending on the ligand and the molecular structure.

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Section: Methodsmentioning

confidence: 99%

“…[21] Hydroxylation of 17a-AMPY compound 16: We started our investigations with the quasi-axial 17a-amine 15 [22] (Scheme 4). The solid-state structure of the corresponding imine 16 exhibits the expected small torsional angle for 17bH-C17-17aN=C (9.88) and the E configuration of the C=N double bond was confirmed.…”

mentioning

confidence: 99%

Intramolecular γ‐Hydroxylations of Nonactivated CH Bonds with Copper Complexes and Molecular Oxygen

Schönecker

Zheldakova

Lange

et al. 2004

Chemistry A European J

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“…The desired trans-1,2-disubstituted cyclopropane with two new chiral centers could be obtained in a high yield; however, with a very low diastereoselectivity ( 1 H NMR-investigation). A simple hydrolysis of the C@N double bond could be achieved via chromatography, which resulted in the 17b-amine and a mixture of the two enantiomers of the known trans-2-phenyl-cyclopropano-1-carbaldehyde (ratio determined by gas chromatography with a chiral column) [25]. A similar result was obtained starting with the a,b-unsaturated imine from the cis-16b-amino-17b-alcohol.…”

Section: Pd-catalysed Cyclopropanation Of Ab-unsaturated Iminesmentioning

confidence: 77%

“…With the imine of the cis-16a-amino-17a-diphenyl-tertbutylsilyloxy compound, the diastereoselectivity could be improved to a ratio of 5:95. After hydrolysis, the (1R,2R)-trans-2-phenyl-cyclopropano-1-carbaldehyde is now the main enantiomer [25].…”

Section: Pd-catalysed Cyclopropanation Of Ab-unsaturated Iminesmentioning

confidence: 99%

Steroids as chiral model compounds for selective reactions with metals

Schönecker

Lange

2006

Journal of Organometallic Chemistry

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“…Recent reports have established that similar ring systems constitute valuable substrates for A-ring functionalised steroidal scaffolds [12] with potential application in asymmetric synthesis [13], supramolecular recognition [14], cancer chemotherapy [15], steroid receptor-based imaging [16] and material science [17]. In this regard, the 4-(and/or 2)-nitro-17β-estradiol (Figure 1) have been exploited as compounds with anticancer activity and probes for ligand-receptor interaction studies [18][19][20].…”

Section: -Nitro-17β-estradiolmentioning

confidence: 99%

Synthesis of Novel Nitro-substituted Triaryl Pyrazole Derivatives as Potential Estrogen Receptor Ligands

et al. 2007

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Novel tetrasubstituted pyrazole derivatives bearing a nitro substituent on their A-phenol ring were synthesized and their binding affinity towards the estrogen receptor (ER) subtypes ERα and ERβ was determined. Among compounds tested, the 2-nitrophenol derivative 5c was found to bind satisfactorily to both estrogen receptor subtypes (RBAα=5.17 and RBAβ=3.27). In general, the introduction of a nitro group into the A ring of these compounds was found to benefit their ERβ binding abilities.

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O-Silylated steroidal cis-aminoalcohols as chiral auxiliaries: highly diastereoselective Pd-catalyzed cyclopropanation of α,β-unsaturated aldimines

Cited by 19 publications

References 23 publications

Intramolecular γ‐Hydroxylations of Nonactivated CH Bonds with Copper Complexes and Molecular Oxygen

Intramolecular γ‐Hydroxylations of Nonactivated CH Bonds with Copper Complexes and Molecular Oxygen

Steroids as chiral model compounds for selective reactions with metals

Synthesis of Novel Nitro-substituted Triaryl Pyrazole Derivatives as Potential Estrogen Receptor Ligands

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