406949-73-3Relevant academic research and scientific papers
A novel method for the asymmetric synthesis of 4,4-disubstituted 2-cyclopentenones from optically active 1-chlorovinyl p-tolyl sulfoxides and its application to the asymmetric total synthesis of (+)-α-cuparenone
Satoh, Tsuyoshi,Yoshida, Masaaki,Takahashi, Yasuhiro,Ota, Hiroyuki
, p. 281 - 288 (2007/10/03)
Enantiomerically pure 1-chlorovinyl p-tolyl sulfoxides having two different substituents at the 2-position were synthesized from unsymmetrical ketones and (R)-(-)-chloromethyl p-tolyl sulfoxide in three steps. Treatment of the 1-chlorovinyl p-tolyl sulfoxides with cyanomethyllithium at -78°C to room temperature gave optically active 2-amino-1-cyano-5,5-disubstituted-1,3-cyclopentadienes in high yields with very high asymmetric induction from the stereogenic center of the sulfoxide moiety. A mechanism for the asymmetric induction is proposed. The products were treated with phosphoric acid in acetic acid at reflux temperature to give enantiomerically pure 4,4-disubstituted 2-cyclopentenones in good yields. As an application of this synthetic method, a relatively short (seven steps) total asymmetric synthesis of (+)-α-cuparenone from methyl 4-methylphenyl ketone is described.
Asymmetric synthesis of 4,4-disubstituted 2-cyclopentenones from optically active 1-chlorovinyl p-tolyl sulfoxides and cyanomethyllithium with formation of a quaternary chiral center
Satoh, Tsuyoshi,Yoshida, Masaaki,Ota, Hiroyuki
, p. 9241 - 9244 (2007/10/03)
Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides having two different substituents at the 2-position, which were synthesized from unsymmetrical ketones and (R)-(-)-chloromethyl p-tolyl sulfoxide in three steps, with cyanomethyllithium gave optically active 2-amino-1-cyano-5,5-disubstituted-1,3-cyclopentadienes with very high asymmetric induction from the sulfoxide chiral center. The products were converted to the enantiomerically pure 4,4-disubstituted 2-cyclopentenones by heating with phosphoric acid in acetic acid.
