DuPhos
DuPhos是一种用于不对称合成中的不对称配体。DuPhos之名称取自其研发公司(DuP,杜邦公司)和化合物的种类:膦杂环(Phos)。这种二膦配体首先由化学家M.J. Burk于1991年发现, [1][2] 并首次在不对称氢化反应中,成功地将特定的烯基酰氨酯还原为氨基酸前体:
同期发现其他有机磷不对称配体有诸如:DIPAMP、BINOL和Chiraphos,而后期发现了一批新的配体被证明比前者更具活性。
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描述 [编辑]
DuPhos配体由两个2,5-烷基取代膦杂环(THF的磷类似物)通过1,2-苯桥连而成。这里的烷基可以是:甲基、乙基、丙基或异丙基。DuPhos的类似物,双(二甲基膦)乙烷或BPE配体[3][4] 相当于苯基桥被1,2-乙基所替代之产物。该两种化合物都可通过相应的手性二醇化合物,转化为环状硫酸盐,继而与双锂二苯基膦反应制备获得。DuPhos配体中,磷原子属于富电子原子团,使形成的金属络合物具有强活性。磷原子还引入了一种假-手性,使对映体选择性不受整个分子的化学构象影响。[5]
DuPhos的另一种早期应用,是通过还原胺化反应合成非天然手性氨基酸:[6] 如先通过二苯甲酮和苯甲酰氯合成的腙得到亚胺,而后在DuPhos催化下发生不对称氢化反应,最后脱去苯甲酰保护基得到非天然手性氨基酸产物:[7]
在早期的过渡金属催化反应中,铑是常用的催化剂,直到在1995年才引入了钌催化剂,[8] 实例是氢化还原β-酮酯的羰基,合成手性的β-羟基酯:
应用 [编辑]
DuPhos的一个不对称合成实例为催化“脱氢华法林”氢化为华法林的反应:[9]
BozPhos配体 [编辑]
使用硼烷二甲硫醚作为保护基,在过氧化氢条件下单氧化(R,R)-Me-Duphos即得到BozPhos。[11][12]
该配体可用于铜-催化的二有机锌试剂对N-二苯基次磷酰亚胺的不对称加成反应。
参考文献 [编辑]
- ^ C2-symmetric bis(phospholanes) and their use in highly enantioselective hydrogenation reactions Mark J. Burk J. Am. Chem. Soc., 1991, 113 (22), pp 8518–8519 doi:10.1021/ja00022a047
- ^ Preparation and use of C2-symmetric bis(phospholanes): production of .alpha.-amino acid derivatives via highly enantioselective hydrogenation reactions Mark J. Burk, John E. Feaster, William A. Nugent, Richard L. Harlow J. Am. Chem. Soc., 1993, 115 (22), pp 10125–10138 doi:10.1021/ja00075a031
- ^ New electron-rich chiral phosphines for asymmetric catalysis Mark J. Burk, John E. Feaster, Richard L. Harlow Organometallics, 1990, 9 (10), pp 2653–2655 doi:10.1021/om00160a010
- ^ New chiral phospholanes; Synthesis, characterization, and use in asymmetric hydrogenation reactions Tetrahedron: Asymmetry, Volume 2, Issue 7, 1991, Pages 569-592 Mark J. Burk, John E. Feaster, Richard L. Harlow错误:指定的DOI无效!
- ^ Recent Developments in Catalytic Asymmetric Hydrogenation Employing P-Chirogenic Diphosphine Ligands Karen V. L. Crépy, Tsuneo Imamoto Advanced Synthesis & Catalysis Volume 345 Issue 1-2, Pages 79 - 101 2003 doi:10.1002/adsc.200390031
- ^ Enantioselective hydrogenation of the C:N group: a catalytic asymmetric reductive amination procedure Mark J. Burk, John E. Feaster J. Am. Chem. Soc., 1992, 114 (15), pp 6266–6267 doi:10.1021/ja00041a067
- ^ Catalytic asymmetric reductive amination of ketones via highly enantioselective hydrogenation of the C=N double bond Mark J. Burk , Jose P. Martinez, John E. Feaster and Nick Cosford Tetrahedron Volume 50, Issue 15, 11 April 1994, Pages 4399-4428错误:指定的DOI无效!
- ^ Practical asymmetric hydrogenation of β-keto esters at atmospheric pressure using chiral Ru (II) catalysts J. P. Genêt, V. Ratovelomanana-Vidal, M. C. Caño de Andrade, X. Pfister, P. Guerreiro and J. Y. Lenoir Tetrahedron Letters Volume 36, Issue 27, 3 July 1995, Pages 4801-4804错误:指定的DOI无效!
- ^ The first practical asymmetric synthesis of R and S-Warfarin Andrea Robinson and Hui-Yin Li John Feaster Tetrahedron Letters Volume 37, Issue 46, 11 November 1996, Pages 8321-8324错误:指定的DOI无效!
- ^ A highly enantioselective asymmetric hydrogenation route to β-(2R,3S)-methyltryptophan R. Scott Hoerrner, David Askin, R.P. Volante and Paul J. Reider Tetrahedron Letters Volume 39, Issue 21, 21 May 1998, Pages 3455-3458 doi:10.1016/S0040-4039(98)00604-2
- ^ Alexandre Côté, Jean-Nicolas Desrosiers, Alessandro A. Boezio, and André B. Charette (2006). "Preparation of enantiomerically pure (R,R)-BozPhos". Org. Synth. 83: 1.
- ^ Jean-Nicolas Desrosiers, Alexandre Côté, Alessandro A. Boezio, and André B. Charette (2006). "Preparation of enantiomerically enriched (1S)-1-Phenylpropan-1-amine hydrochloride by a catalytic addition of diorganozinc reagents to imines". Org. Synth. 83: 5.