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Stereoselective Syntheses of Alcohols, XXV. Generation of Enol Borates and Their Addition to Aldehydes
Author(s) -
Hoffmann Reinhard W.,
Ditrich Klaus,
Fröch Sybille
Publication year - 1987
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.198719870858
Subject(s) - enol , chemistry , boron , aldol reaction , aldehyde , ketone , lithium (medication) , borylation , organic chemistry , medicinal chemistry , catalysis , medicine , endocrinology , alkyl , aryl
Ketone‐derived enol borates, especially those having a 4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolane unit, are stable compounds, which have been prepared either by borylation of lithium enolates or by oxidation of vinylboronates. These E ‐ or Z ‐enol borates add to aldehydes in a stereoconvergent reaction leading to syn ‐aldols. Aldehyde‐derived enol borates have a high tendency towards polymerization. Their in‐situ addition to aldehydes generates 4‐alkoxy‐1,3,2‐dioxaborinanes, which are internally protected aldols.