Microbially-aided preparation of (S)-2-Methoxycyclohexanone key intermediate in the synthesis of Sanfetrinem
摘要:
(S) 2-Methoxycyclohexanone 1, useful intermediate in the synthesis of Sanfetrinem 2, is obtained from (S) alpha-benzylidene cyclohexanol 4, derived from the ketone 3 through a short sequence involving as key step yeast reduction of the carbonyl group. The (R) enantiomer of 1 is similarly accessible from the (R) enantiomer of 4 obtained either upon Candida lipolytica-mediated reduction of 3 or from (R,S)-4 by porcine pancreatic lipase catalyzed acetylation with vinyl acetate. Also the saturated carbinols 7 and 8, which accompany 4 in the microbial reduction of 3, are converted into 1 through unexceptional steps. Nocardia opaca, Pichia etchelsii and Mucor subtilissimus provide from 3 upon reduction (S)-configurated 4, 7 and 8 possessing moderate-high ee values. (C) 1997, Elsevier Science Ltd.
Enantioselective reduction of α,β-enones using an oxazaborolidine catalyst generated in situ from a chiral lactam alcohol
作者:Yasuhiro Kawanami、Yudai Mikami、Kazuya Kiguchi、Yuki Harauchi、Ryo C. Yanagita
DOI:10.1016/j.tetasy.2011.10.018
日期:2011.11
The oxazaborolidine catalyst prepared in situ from the chiral lactam alcohol 3 and 4-iodophenoxyborane was found to catalyze the enantioselective reduction of α,β-enones at −40 °C with a high level of enantioselectivity of up to 90% ee.
A new type of ferrocene-based phosphine-oxazoline ligand has been prepared over a few simple steps. An iridium complex of this ligand is air stable and exhibits excellent performance for the asymmetric hydrogenation of simple ketones (up to 98% yield, up to 99% ee, and 20 000 S/C). Exo-α,β-unsaturated cyclic ketones could be regiospecifically hydrogenated to give chiral allylic alcohols with good results
通过几个简单的步骤即可制备出新型的二茂铁基膦-恶唑啉配体。该配体的铱络合物是空气稳定的,并且对于简单的酮的不对称氢化表现出出色的性能(最高98%的收率,最高99%的ee和20000 S / C)。Exo -α,β-不饱和环状酮可被区域特异性氢化,得到手性烯丙基醇,效果良好。这项研究表明,P,N-配体也可以有效地促进Ir催化的不对称氢化反应,而无需NH-氢键辅助。
Ruthenium-catalysed synthesis of chiral exocyclic allylic alcohols <i>via</i> chemoselective transfer hydrogenation of 2-arylidene cycloalkanones
exclusive asymmetric reduction of CO bonds of 2-arylidene four-, five-, six-, and seven-membered cycloalkanones has been studied systematically. The asymmetric transfer hydrogenation was performed using a robust and commercially available chiral diamine-derived ruthenium complex as a catalyst and HCOOH/Et3N as a hydrogen source under mild conditions, giving 51 examples of chiral exocyclic allylic alcohols
已经系统地研究了2-芳基四,五,六和七元环烷烃的C O键的排他不对称还原。在温和条件下,使用稳固且可商购的手性二胺衍生钌络合物作为催化剂,HCOOH / Et 3 N作为氢源,进行不对称转移氢化,给出了51种示例手性环外烯丙基醇,收率高达96%, 99%ee。该方法也适用于抗炎洛索洛芬和天然产物(-)-goniomitine的活性中间体的克级合成。
RuPHOX-Ru-Catalyzed Selective Asymmetric Hydrogenation of Exocyclic α,β-Unsaturated Pentanones
A RuPHOX-Ru catalyzed selective asymmetrichydrogenation of exocyclic α,β-unsaturated ketones has been developed, furnishing the corresponding chiral exocyclic allylic alcohols in high yields and with up to >99.5% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 10000 S/C) without any loss in reaction activity and enantioselectivity. The resulting hydrogenated
已开发出RuPHOX-Ru催化的环外α,β-不饱和酮的选择性不对称氢化,可提供高收率和最高> 99.5%ee的相应手性环外烯丙基醇。该反应可以以克级进行,具有相对较低的催化剂负载量(最高10000 S / C),而没有任何反应活性和对映选择性的损失。所得的氢化产物可以容易地转化为具有高不对称性能的几种生物活性化合物。不对称方案为合成手性环外烯丙基醇提供了一种有效的方法。
Highly Enantioselective Hydrogenation of α-Arylmethylene Cycloalkanones Catalyzed by Iridium Complexes of Chiral Spiro Aminophosphine Ligands
The highly efficient asymmetric hydrogenation of alpha-arylmethylene cycloalkanones catalyzed by Ir-complexes of chiral spiro aminophosphine ligands was developed, providing chiral exo-cyclic allylic alcohols at high yields with excellent enantioselectivities (up to 97% ee) and high turnover numbers (S/C up to 10,000). This new reaction provided an efficient method for the synthesis of the key intermediate
开发了由手性螺氨基膦配体的 Ir 配合物催化的 α-芳基亚甲基环烷酮的高效不对称氢化,以高产率提供手性外环烯丙醇,具有优异的对映选择性(高达 97% ee)和高转换数(S/ C 高达 10,000)。这一新反应为合成抗炎洛索洛芬活性形式的关键中间体提供了一种有效的方法。