Vollständige enantiotope Differenzierung zwischen den Kohlenstoffatomen einer Doppelbindung bei der Umsetzung von Diolaten mit <i>meso</i>‐Bis(phenylsulfonyl)alkenen ‐ Synthese enantiomerenreiner Ketone

Cossu, Sergio; Delucchi, O.; Pasetto, Paolo

doi:10.1002/ange.19971091347

Cited by 5 publications

(2 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To obtain enantioenriched 7 (Figure 4 A), we used the methodology for enantiotopic discrimination of sp 2 -hybridized carbon atoms in meso-norbornene compounds. [50,51] In particular, it has been shown that bis-A C H T U N G T R E N N U N G (phenyl)sulfonylalkenes of type 9 could be treated with a chiral diol to give one diastereomeric acetal in excess. Accordingly, we attempted the desymmetrization of meso-9 with (R)-1,1'-bi-2-naphthol (BINOL).…”

Section: The Condensation Of Enantioenriched Pyrromethanecarbinolmentioning

confidence: 99%

“…Accordingly, we attempted the desymmetrization of meso-9 with (R)-1,1'-bi-2-naphthol (BINOL). [51] The diastereopure product was indeed isolated, but all attempts for removing (by hydrolyzing) the chiral auxiliary failed. The reaction of bis(phenylsulfonyl)benzonorbornadiene 9 with an equimolar amount of sodium salt of (R,R)-(+)-methoxy-1,2-diphenylethanol, however, gave enol ether 10, which was easily hydrolyzed and reduced into 11.…”

Section: The Condensation Of Enantioenriched Pyrromethanecarbinolmentioning

confidence: 99%

See 1 more Smart Citation

The Role of Chirality in Directing the Formation of Cup‐Shaped Porphyrins and the Coordination Characteristics of such Hosts

Wang¹,

Turner²,

Zujović³

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

Cup-shaped porphyrin 1a has four norbornane rings for encircling space and this type of host could be of interest in supramolecular and catalytic chemistry. We used (1)H NMR spectroscopy to investigate the acid-catalyzed (pTsOH in CHCl(3) and TFA in CH(3)CN) condensation of racemic, enantioenriched (80-85 % enantiomeric excess (ee)), and enantiopure (99 % ee) pyrromethanecarbinol 7 into 1a. We found that the oligomerization of racemic 7(rac) would give 1a-d in the ratio different from the statistical one, though a minuscule quantity of 1a (<5 %) formed. The oligomerization of enantioenriched 7 (80-85 % ee), however, led to the formation of greater amounts of 1a (31-47 %) along with other stereoisomers 1b-d. Importantly, pTsOH catalyzed the conversion of enantiopure 7 (99 % ee) into 1a (>95 % diastereomeric excess (de), 25 % overall yield) in CHCl(3) although prolonged reaction times or greater concentration of the catalytic acid gave rise to 1b-d at the expense of 1a. The metallation of 1 a with Zn(OAc)(2) led to the formation of Zn(II) -1 a and we used computational (DFT: RI-BP86/SV(P),TZVP) and experimental ((1)H NMR spectroscopy) methods to study the partitioning of smaller N-methylimidazole 13 (94 Å(3) ) and bigger 1,5-dicyclohexylimidazole 14 (268 Å(3)) between the inner and outer side of the host. We found that bigger 14 was mostly encapsulated (90 %) inside Zn(II) -1 a at 298.0 K, whereas smaller 13 would equally partition between the two sides of the host. Furthermore, the out/in equilibrium was, in the case of 14-Zn(II) -1a, favored by entropy (TΔS°(out/in) =3.5±0.1 kcal mol(-1)) indicating that perhaps differential solvation of the coordinated ligand assisted the encapsulation.

show abstract

Section: The Condensation Of Enantioenriched Pyrromethanecarbinolmentioning

confidence: 99%

Section: The Condensation Of Enantioenriched Pyrromethanecarbinolmentioning

confidence: 99%

The Role of Chirality in Directing the Formation of Cup‐Shaped Porphyrins and the Coordination Characteristics of such Hosts

Wang¹,

Turner²,

Zujović³

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

show abstract

Enantiomeric Discrimination in a Reiterative Domino Coupling Process: CuI-mediatedSyn Cyclotrimerization of Racemic Polycyclic Trimethylstannyl Bromonorbornadienes

et al. 2001

Self Cite

View full text Add to dashboard Cite

The fundamental concept of molecular discrimination considers the ability of a chemical object to identify, in the presence of alternative possibilities, a defined chemical counterpart through specific interactions. [1] When discrimination depends on the chiral properties of the chemical partners, only one of the events that derive from the possible stereochemical combinations can be realized. [1] In this context, a peculiar discrimination was observed during the self-coupling of racemic ketones that possess the bicyclo[2.2.1]heptene skeleton, either by means of aldol reactions or via organocuprate derivatives. The main feature of the reported uration in the formation of the unsupported metal ± metal bond. Furthermore, the steric bulk of the pyridonate rings does not hinder the formation the unsupported metal ± metal bond. Therefore, one could envisage the accessibility of a hypothetical tetrametallic chain made of two HT units.With the experimental confirmation of the intervention of HT dimers in tetrametallic chains, it seems likely that the lack of HT-pyridonate dimers in the platinum blues complexes should be attributed mainly to thermodynamic reasons rather than to steric factors.[1] For leading references see: a) R. Cle Â rac, F.

show abstract

Enantiomeric Discrimination in a Reiterative Domino Coupling Process: CuI-mediated Syn Cyclotrimerization of Racemic Polycyclic Trimethylstannyl Bromonorbornadienes This work was funded by MURST (Rome) within the national project “Stereoselezione in Sintesi Organica. Metodologie e Applicazioni”.

Cossu¹,

Cimenti²,

Peluso³

et al. 2001

Angew. Chem. Int. Ed.

Self Cite

View full text Add to dashboard Cite

show abstract

Vollständige enantiotope Differenzierung zwischen den Kohlenstoffatomen einer Doppelbindung bei der Umsetzung von Diolaten mit meso‐Bis(phenylsulfonyl)alkenen ‐ Synthese enantiomerenreiner Ketone

Abstract: Die Desymmetrisierung von Bis(phenylsulfonyl)alkenen 1 liefert das gewünschte Enantiomer polycyclischer Ketone schnell, in hohen Ausbeuten und in enantiomerenreiner Form (siehe unten); 1 ist ebenfalls leicht in Multigramm‐Mengen zugänglich.magnified image

Cited by 5 publications

References 29 publications

The Role of Chirality in Directing the Formation of Cup‐Shaped Porphyrins and the Coordination Characteristics of such Hosts

The Role of Chirality in Directing the Formation of Cup‐Shaped Porphyrins and the Coordination Characteristics of such Hosts

Enantiomeric Discrimination in a Reiterative Domino Coupling Process: CuI-mediatedSyn Cyclotrimerization of Racemic Polycyclic Trimethylstannyl Bromonorbornadienes

Enantiomeric Discrimination in a Reiterative Domino Coupling Process: CuI-mediated Syn Cyclotrimerization of Racemic Polycyclic Trimethylstannyl Bromonorbornadienes This work was funded by MURST (Rome) within the national project “Stereoselezione in Sintesi Organica. Metodologie e Applicazioni”.

Contact Info

Product

Resources

About