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Beiträge zur Chemie des Bors, 202. Borylierung von Aminosäuren mit einem Amino‐imino‐boran
Author(s) -
Geisberger Gilbert,
Nöth Heinrich
Publication year - 1990
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19901230503
Subject(s) - chemistry , borane , amino acid , substituent , ring (chemistry) , medicinal chemistry , stereochemistry , yield (engineering) , carbon atom , organic chemistry , catalysis , biochemistry , materials science , metallurgy
Contributions to the Chemistry of Boron, 202 1 ). – Borylation of Amino Acids by an Amino‐imino‐borane Reactions of ( tert ‐butylimino)(2,2,6,6‐tetramethylpiperidino)‐borane ( 3 ) with amino acid esters or N,N ‐dimethyl amino acids lead to the N ‐borylated products 5 and boryl esters 11 , respectively. Amino acids and 3 yield the O,N ‐bis‐boryl compounds 13 and/or 1,3,2‐oxazaborolidin‐5‐ones 14 , depending on the size of the organyl substituent R at the α‐carbon atom of the amino acid. Increasing the bulk of this group favours the formation of 14 with elimination of tert ‐butylamine. The five‐membered OBNCC ring of 14 is planar according to an X‐ray structure analysis of 14e . (2,6‐Diisopropylphenylimino)(2,2,6,6‐tetramethylpiperidino)borane reacts with amino acids similar to 3 , but tetramethylpiperidine is eliminated on ring formation to produce 20 . N ‐Monoalkyl amino acids and 3 predominantly give oxazaborolidin‐5‐ones.