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Highly Stereoselective Total Synthesis of Multiply Protected 3‐Amino‐3,6‐dideoxyaldohexoses (Mycosamine/Mycaminose) by Aldol Condensation Reaction, Mediated by Tin Triflate, of Tricarbonyliron/α‐Aminodienone Complexes
Author(s) -
FranckNeumann Michel,
MieschGross Laurence,
Gateau Christelle
Publication year - 2000
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 - 10.1002/1099-0690(200011)2000:22<3693::aid-ejoc3693>3.0.co;2-s
Subject(s) - chemistry , stereoselectivity , stereochemistry , trifluoromethanesulfonate , diastereomer , yield (engineering) , aldol condensation , enol ether , diol , enantiomer , medicinal chemistry , organic chemistry , catalysis , materials science , metallurgy
The divalent tin enol ether of the racemic complex between N ‐BOC‐α‐aminoheptadienone and tricarbonyliron reacts with both enantiomers of protected lactaldehydes to yield predominantly one optically active, easily isolable ketol diastereoisomer (45%). From the enantiomerically pure ( S )‐(+) complex and ( R )‐(+)‐ tert ‐butyldimethylsilyloxylactaldehyde, the major ketol is obtained almost exclusively (isolated yield 86%). From there, the multiply protected 3‐amino‐3,6‐dideoxy‐ D ‐aldohexose mycosamine is obtained in a few high‐yield steps (decomplexation, stereospecific reduction to an anti ‐1,3‐diol, transformation into a diacetate and ozonolysis; absolute configurations S , S , S , R ). Reduction of the ketol before decomplexation completely reverses the stereochemistry of the reaction [control by the Fe(CO) 3 and not by the hydroxy group → syn ‐diol], also giving access to the ( R , S , S , R ) series (configuration of the N,N ‐dimethylated mycaminose). The key structures were determined by X‐ray diffraction.