Carbonylative coupling of organozinc reagents in the presence and absence of aryl iodides: synthesis of unsymmetrical and symmetrical ketones
作者:Richard F. W. Jackson、Debra Turner、Michael H. Block
DOI:10.1039/a606394b
日期:——
The utility of the palladium(0) catalysed reaction of the
iodoalanine-derived organozinc reagent 6a with functionalised
aryl iodides, under a carbon monoxide atmosphere, to give
protected 4-aryl-4-oxo α-amino acids 8, is illustrated by
a short synthesis of L-kynurenine 4. Treatment of
functionalised organozinc reagents with catalytic
tetrakis(triphenylphosphine)palladium(0) under an atmosphere of
carbon monoxide in the absence of any electrophile leads to the
formation of symmetrical functionalised ketones 9 in good yields.
This reaction is illustrated by a one-step synthesis of protected
(2S,6S)-4-oxo-2,6-diaminopimelic acid 9a from
commercially available compounds. It has been established that
adventitious molecular oxygen plays a key role in the formation
of the symmetrical ketones 9, and that rigorous exclusion of
oxygen can result in substantially higher yields of ketones 8 in
the cross-coupling with some aromatic iodides.
钯(0)催化的碘丙氨酸衍生的有机锌试剂6a与功能化芳基碘在CO气氛下的反应,可得到保护的4-芳基-4-氧代α-氨基酸8,其应用由L-犬尿氨酸4的简短合成说明。在无任何亲电试剂的情况下,功能化有机锌试剂在碳 monoxide 气氛下与催化剂四(三苯基膦)钯(0)反应,能以良好产率形成对称的功能化酮9。此反应由从市售化合物一步合成保护的(2S,6S)-4-氧代-2,6-二氨基庚二酸9a说明。已确定偶然的分子氧在形成对称酮9中起关键作用,且严格排除氧气可导致在与某些芳香碘的交叉耦合中酮8的产量显著提高。