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烷基硼酸和硼酸酯类
(Alkylboronic acids and Alkylboronates)
以双(pinacolato)二硼化硼为硼源的温和钯催化伯溴化一级烷基溴化物的过程在烷基溴化物底物上可耐受广泛的官能团,并且在二级溴化物存在下提供完全的选择性。这一方法已扩展到烷基碘化物和烷基对磺酸酯的使用,以及以双(新戊基乙醇酸)二硼烷为硼源的硼化反应.( J. Org. Chem., 2012, 77, 6629-6633.)
极少量的溴化锰和四甲基乙二胺(TMEDA)催化了(双)苯甲酸二硼与多种卤代烷的交叉偶联反应。此方法允许访问一级、二级和三级硼酸酯.( J. Am. Chem. Soc., 2016, 138, 6139-6142.)
用磁铁矿浸渍铜对烯烃进行硼化反应的一个简单方法显示了非常广阔的范围。所有类型的烯烃都可以用于类似的结果。催化剂可以被磁性地去除并重复使用多次,显示出类似的活性. ( J. Org. Chem., 2010, 75, 3458-3460.)
烯丙基硼酸和硼酸酯类
(Allylboronic acids and Allylboronates)
脂肪族、芳香族、杂芳香族、乙烯基或烯丙基格氏试剂在四氢呋喃环境温度下与吡那考硼烷反应,得到相应的吡那考硼酸盐。最初形成的二烯氧基烷基硼氢化中间物迅速消除了溴化氢镁,并以很好的收率提供了产品硼酯。这种反应也可以在巴比尔条件下进行。(J. Org. Chem., 2011, 76, 9602-9610.)
Readily available allylic acetates are converted to allylic boronates catalyzed by Ni/PCy3 or Ni/PPh3 complexes with high levels of stereoselectivity and in good yields, whereas the borylation of allylic halides can be accomplished with commercially available Pd catalysts [e.g., Pd2(dba)3, PdCl2, Pd/C].(Org. Lett., 2012, 14, 1363-1365.)
乙烯基硼酸和硼酸酯类
(Vinylboronic acids and Vinylboronates)
Carboxylic acids are able to catalyze the direct hydroboration of various terminal and internal alkynes with pinacolborane without using any metal catalysts. This hydroboration exhibits a broad functional groups compatibility and gives the corresponding alkenyl diboronates and monoboronates in very good yields with exclusive regio- and stereoselectivities. (Org. Lett., 2014, 16, 4670-4673.)
A cobalt-catalyzed method for the diboration of terminal alkynes with B2Pin2 proceeds efficiently at 23°C with excellent 1,1-selectivity and broad functional group tolerance. With the unsymmetrical diboron reagent PinB-BDan, stereoselective 1,1-diboration provided products with two boron substituents that exhibit differential reactivity. ( J. Am. Chem. Soc., 2017, 139, 3868-3875.)
苄基硼酸和硼酸酯类
(Benzylboronic acids and Benzylboronates)
A catalytic amount of Mg as the only metal enables a reductive coupling between benzyl halides and pinacolborane. HBpin acts both as an electrophile and as a reducing agent to regenerate an organomagnesium species in situ. An hydride oxidation mechanism is proposed on the basis of DFT calculations. ( J. Am. Chem. Soc., 2010, 132, 11825-11827.)
A regioselective hydroboration of vinylarenes catalyzed by a Rh(I)-DPPB complex proceeded rapidly when DMAP was used as an additive to furnish the desired boronates in good to excellent yield with high regioselectivity. ( Synlett, 2008, 3231-3233.)
芳基硼酸和硼酸酯类
(Arylboronic acids and Arylboronates)
A general and convenient protocol for the electrophilic borylation of aryl Grignard reagents prepared from arylbromides by direct insertion of magnesium in the presence of LiCl or by Mg/Br exchange with iPrMgCl·LiCl enables the synthesis of various aryl boronic acids in a straightforward manner in excellent yields at 0°C.(Org. Lett., 2011, 13, 4479-4481.)
A simple continuous flow setup for handling and performing of organolithium chemistry on the multigram scale enables the synthesis of various compounds following a reaction sequence of Hal/Li exchange and electrophilic quench. It was possible to synthesize building blocks within a 1 s total reaction time and with a remarkable throughput of 60 g / h.(Org. Lett., 2016, 18, 3630-3633.)
丙二烯基硼酸和硼酸酯类
(Allenylboronic acids and Allenylboronates)
A copper-catalyzed synthesis of benzyl-, allyl-, and allenyl-boronates from benzylic, allylic, and propargylic alcohols, respectively, exhibits a broad reaction scope and high efficiency under mild conditions. Preliminarily mechanistic studies suggest that nucleophilic substitution is involved in this reaction. (Org. Lett., 2017, 19, 1204-1207.)
Bimetallic Pd/Cu and Pd/Ag catalytic systems enable a stererospecifically borylation of propargylic alcohol derivatives via formal SN2′ pathways to give allenyl boronates. Opening of propargyl epoxides leads to 1,2-diborylated butadienes probably via en allenylboronate intermediate. ( J. Am. Chem. Soc., 2014, 136, 7359-7542.)
药物合成中应用实例:
他伐硼罗(Tavaborole),商品名 KERYDIN,由Anacor研发生产,2014年7月FDA批准上市,属于羟硼类(oxaborole)抗真菌药,适用于红色毛藓菌或须藓毛藓菌感染的趾甲真菌病的局部治疗,目前该药品仍然仅在美国地区销售,国内尚无企业进行注册申报。
专利US8115026报道的合成路线,是以2-溴-5-氟苯甲醛为起始原料,不需要进行醛基的保护,使用Pd催化剂,与嚬吶醇硼酸酯反应得到苯硼酸酯中间体,避免了高活性的丁基锂试剂的使用,再水解得到苯硼酸衍生物,随后再将醛基还原为醇,关环即得到目标产物。
硼替佐米(Bortezomib), 作为以蛋白酶体为靶标的首创药物, 也是第一个问世的含有机硼酸的小分子化合物, 硼酸特异性地与蛋白酶体的重要残基发生共价键结合, 是硼替佐米高选择性的结构基础。
硼替佐米由千年制药(Millennium)开发,商品名VELCADE®,于2003年5月13日获FDA批准。本品可联合美法仑和泼尼松(MP方案)用于既往未经治疗的且不适合大剂量化疗和骨髓抑制的多发性骨髓瘤患者的治疗;或单药用于至少接受过一种或一种以上治疗后复发的多发性骨髓瘤患者的治疗;本品可用于复发或难治性套细胞淋巴瘤患者的治疗,此患者在使用本品前至少接受过一种治疗。
硼提佐米的合成可以通过吡嗪酸和L-苯丙氨酸反应得到中间体(2), 再和含硼基保护基的甲基丁烷硼酸盐(3)反应得到中间体(4), 最后用异丁基硼酸反应脱去硼基保护基得到目标产物硼替佐米。
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