A one-pot two-step synthesis of tertiary alcohols combining the biocatalytic laccase/TEMPO oxidation system with organolithium reagents in aerobic aqueous media at room temperature
study. The unprecedented combination of the catalytic oxidation of secondary alcohols by the system laccase/TEMPO with the ultrafast addition (3 s reaction time) of polar organometallic reagents (RLi/RMgX) to the in situ formed ketones, run under air at roomtemperature, allows the straightforward and chemoselective synthesis of tertiary alcohols with broad substrate scope and excellent conversions
Synthesis of β-acetoxy alcohols by PhI(OAc)<sub>2</sub>-mediated metal-free diastereoselective β-acetoxylation of alcohols
作者:Chun-Yang Zhao、Liang-Gui Li、Qing-Rong Liu、Cheng-Xue Pan、Gui-Fa Su、Dong-Liang Mo
DOI:10.1039/c6ob01203e
日期:——
β-Acetoxy alcohols can be synthesized in good yields with excellent diastereoselectivity from tertiary alcohols through PhI(OAc)2-mediated metal-free β-acetoxylation. Mechanistic studies showed that the β-acetoxylation process might undergo dehydration and sequential highly regioselective and diastereoseletive dioxygenation. Gram scale and diverse useful scaffolds could be prepared via this β-acetoxylation
A practical and useful, catalyticenantioselective method has been developed for the synthesis of tertiary diaryl and aryl heteroaryl carbinols starting from commercially available aromatic ketones and aryl or heteroaryl bromides. In this method, organotitanium reagents are generated in situ from the bromides by lithiation with nBuLi followed by transmetallation of the resulting organolithiums with
已经开发了一种实用且有用的催化对映选择性方法,用于从可商购的芳族酮和芳基或杂芳基溴化物开始合成叔二芳基和芳基杂芳基甲醇。在该方法中,通过用n BuLi锂化从溴化物中原位生成有机钛试剂,然后用ClTi(O i Pr)3对所得的有机锂进行金属转移。在(R)-3-(3,5-双三氟甲基苯基)-1,1'-联-2-萘酚(BTFP-BINOL)以高对映选择性和高收率提供了相应的叔醇。反应也可以从呋喃和2-噻吩基锂开始。该方法操作简单,可在10 mmol规模下进行而没有任何困难。
Highly Enantioselective Arylation of Aldehydes and Ketones Using AlArEt<sub>2</sub>(THF) as Aryl Sources
additions to organic carbonyls. Aryl additions of AlArEt2(THF) to aldehydescatalyzed by the titanium(IV) complex of (R)-H8−BINOL were efficient with a short reaction time of 1 h, affording aryl addition products as exclusive or main products in high yields and excellent enantioselectivities of up to 98% ee. Although ethyl additions to aldehydes occurred in minor extent, this study demonstrates that increasing
一系列AlArEt 2(THF)(Ar = Ph(1a),4-MeC 6 H 4(1b),4-MeOC 6 H 4(1c),4-Me 3 SiC 6 H 4(1d),2-由AlEt 2 Br(THF)与ArMgBr的反应合成萘基(1e)。在CDCl 3溶液中,1 H NMR光谱表明,AlArEt 2(THF)化合物以AlAr x Et 3- x(THF)(x= 0、1、2或3)。发现AlArEt 2(THF)化合物是不对称芳基加成到有机羰基化合物中的优良化合物,并且是原子经济的试剂。由(R)-H 8 -BINOL的钛(IV)络合物催化的AlArEt 2(THF)芳基加成醛的反应效率高,反应时间短至1 h,从而以高收率提供芳基加成产物作为独家产物或主要产物以及高达98%ee的优异对映选择性。尽管乙醛中乙醛的添加量很小,但这项研究表明,增加AlArEt 2的含量(THF)从1.2到1.4或到1
Enantioselective addition of organozinc reagents to ketones catalyzed by grafted isoborneolsulfonamide polymers and titanium isopropoxide
作者:Vicente J. Forrat、Diego J. Ramón、Miguel Yus
DOI:10.1016/j.tetasy.2009.01.011
日期:2009.1
The catalytic enantioselective addition of different organozinc reagents, such as diethylzinc, or in situ generated phenylzinc derivatives to simple aryl methyl ketones was accomplished using titanium tetraisopropoxide and a polymeric ligand grafted with trans-1-phenylsulfonylamino-2-isoborneolsulfonylamidocyclohexane, to give the corresponding tertiary alcohols with enantioselectivities of up to >99%