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Asymmetric Synthesis of β‐Methylated Aliphatic Ketones via Lithiated 3‐[( S )‐2‐(Methoxymethyl)pyrrolidino]hex‐3‐ene ☆
Author(s) -
Ahlbrecht Hubertus,
Schmidt Rainer,
Beyer Uwe
Publication year - 1998
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199807)1998:7<1371::aid-ejoc1371>3.0.co;2-k
Subject(s) - chemistry , enamine , alkylation , butyllithium , hydrolysis , lithium (medication) , ketone , ether , chiral auxiliary , stereoselectivity , tin , hexane , medicinal chemistry , organic chemistry , enantioselective synthesis , catalysis , medicine , endocrinology
3‐Substituted aliphatic ketones 10 have been obtained in excellent optical yields by alkylation of the aminoallyllithium compound endo ‐ 8 , a homoenolate equivalent of hexane‐3‐one, using prolinol ether (SMP) as the chiral auxiliary. The intermediate endo ‐ 8 was generated by tin–lithium exchange of the 3‐stannylated enamine 7a with butyllithium. An improved hydrolysis procedure for the resulting enamines is described. Some mechanistic implications with respect to the formation as well as the alkylation of endo ‐ 8 are discussed.