The stereoselective direct aldol reaction of S-phenyl thioesters and aromatic aldehydes promoted by tetrachlorosilane was realized for the first time; the proposed mechanism involves the formation of a chiral cationic hypervalent silicon species and requires the presence of catalytic amounts of a Lewis base, like a chiral phosphine oxide. The reaction affords syn -hydroxy thioesters as major isomers in good yields, high diastereoselectivity (up to 99:1), and up to 92% enantiomeric excess. The absolute configuration of the major isomer was established by converting the product into the corresponding -hydroxy ester. The scope of the reaction was also investigated by employing differently substituted thioesters in combination with different aromatic aldehydes.
Phosphine oxide catalyzed, tetrachlorosilane mediated enantioselective direct aldol reactions of thioesters / S. Rossi, R. Annunziata, F. Cozzi, L. Raimondi. - In: SYNTHESIS. - ISSN 0039-7881. - 47:14(2015), pp. 2113-2124. [10.1055/s-0034-1379914]
Phosphine oxide catalyzed, tetrachlorosilane mediated enantioselective direct aldol reactions of thioesters
S. Rossi;R. AnnunziataSecondo
;F. CozziPenultimo
;L. RaimondiUltimo
2015
Abstract
The stereoselective direct aldol reaction of S-phenyl thioesters and aromatic aldehydes promoted by tetrachlorosilane was realized for the first time; the proposed mechanism involves the formation of a chiral cationic hypervalent silicon species and requires the presence of catalytic amounts of a Lewis base, like a chiral phosphine oxide. The reaction affords syn -hydroxy thioesters as major isomers in good yields, high diastereoselectivity (up to 99:1), and up to 92% enantiomeric excess. The absolute configuration of the major isomer was established by converting the product into the corresponding -hydroxy ester. The scope of the reaction was also investigated by employing differently substituted thioesters in combination with different aromatic aldehydes.File | Dimensione | Formato | |
---|---|---|---|
s-0034-1379914.pdf
accesso aperto
Tipologia:
Publisher's version/PDF
Dimensione
1.07 MB
Formato
Adobe PDF
|
1.07 MB | Adobe PDF | Visualizza/Apri |
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.