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Asymmetric Syntheses via Heterocyclic Intermediates, XXVII. Reactions of Metallated Bislactim Ethers of cyclo(‐L‐Val‐Gly‐) with ( R )‐ and ( S )‐Glyceraldehyde and with ( S )‐Lactaldehyde
Author(s) -
Grauert Matthias,
Schöllkopf Ulrich
Publication year - 1985
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.198519850909
Subject(s) - chemistry , glyceraldehyde , aldol reaction , stereocenter , diastereomer , derivative (finance) , hydrolysis , lithium (medication) , stereochemistry , glyceric acid , ether , acid hydrolysis , adduct , acetylation , stereoselectivity , asymmetric induction , pericyclic reaction , organic chemistry , enantioselective synthesis , catalysis , enzyme , biochemistry , medicine , endocrinology , financial economics , economics , dehydrogenase , gene
Abstract The titanium derivative 3 and the lithium derivative 2 of the bislactim ether 1 of cyclo(‐L‐Val‐Gly‐) react with ( R )‐ and ( S )‐glyceraldehyde (cyclohexylidene‐protected, 9 ) and with ( S )‐lactaldehyde (Mem‐protected, 10 ) to give virtually only one diastereomer. The extent of asymmetric induction is higher for ( S )‐ 9 and 10 than for ( R )‐ 9 . The results can be rationalized on the basis of pericyclic reactions with six‐membered chair‐like transition states. – On acid hydrolysis (subsequent to O ‐acetylation) the aldol‐type addtion products 11 , 12 , and 13 are cleaved to give the amino acid methyl esters 14 , 15 , and 16 with multiple stereocenters. 15 and 16 are enantiomerically and diastereomerically pure.