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Steric Course of the Reduction of Ketoacetal Esters with Alkali Metals in Liquid Ammonia
Author(s) -
Jaisli Fritz,
Sternbach Daniel,
Eschenmoser Albert,
Shibuya Masayuki
Publication year - 1979
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.197906371
Subject(s) - alkali metal , steric effects , alkoxide , chemistry , bridge (graph theory) , ammonia , liquid ammonia , inorganic chemistry , oxygen , reduction (mathematics) , medicinal chemistry , stereochemistry , organic chemistry , catalysis , mathematics , medicine , geometry
The stereochemistry of the reduction of keto groups such as in (1) by alkali metals is influenced by neighboring oxygen functions. Compounds (1) . R 1 , R 2 H, CO 2 Me, give (2) and (3) in th ratio 1:2.5–3. This unexpected finding is explained in terms of stabilization of the axial alkoxide corresponding to (3) by a Li bridge. Na + and K + are too large for bridge formation; they give mainly (2) .