Asymmetric trimethylsilylcyanation of aldehydes utilizing chiral bismuth compounds. A frontier in bismuth mediated synthetic reactions
作者:Makoto Wada、Toshikazu Takahashi、Terutomo Domae、Tomohiro Fukuma、Norikazu Miyoshi、Keith Smith
DOI:10.1016/s0957-4166(97)00570-3
日期:1997.12
found to work efficiently as a versatile catalyst for cyanation of aldehydes with trimethylsilyl cyanide to afford the corresponding cyanohydrins in high yields. Triphenylbismuthan (Ph3Bi) is also effective. The reaction has been applied to the asymmetric cyanation of a variety of aldehydes in high yields with moderate to good enantioselectivities by use of a chiral bismuth catalyst prepared in situ
Exploring the versatility of the Johnson–Claisen rearrangement: access to functionally versatile δ-ethoxycarbonyl-α,β-unsaturated nitriles
作者:Kelly L. Cosgrove、Ross P. McGeary
DOI:10.1016/j.tet.2010.02.045
日期:2010.4
aldehydes were converted to cyanohydrins, by employing either KCN in aqueous acid, or by using TMSCN with catalytic K2CO3, followed by acid hydrolysis of the TMS ether. These cyanohydrins underwent a Claisenrearrangement employing a modified Johnson–Claisen protocol to yield unsaturated nitriles in good yields and with moderate E/Z selectivity.
描述了实际进入δ-乙氧基羰基-α,β-不饱和腈的方法。通过在酸性水溶液中使用KCN或通过将TMSCN与催化性K 2 CO 3一起使用,然后将TMS醚酸水解,可以将α,β-不饱和醛转化为氰醇。这些氰醇经过改良的Johnson-Claisen方案进行了Claisen重排,以高收率和适度的E / Z选择性产生不饱和腈。
Synthesis of 2,4,5-Trisubstituted Oxazoles via Pd-Catalyzed C–H Addition to Nitriles/Cyclization Sequences
作者:Di Zhang、Hao Song、Na Cheng、Wei-Wei Liao
DOI:10.1021/acs.orglett.9b00700
日期:2019.4.19
A practical and flexible intermolecular protocol for the diverse synthesis of trisubstituted oxazole derivatives via a Pd-catalyzed direct C–H addition of electronic-rich heteroarenes to O-acyl cyanohydrins bearing an α-hydrogen/cyclization sequence is described. A wide range of trisubstituted oxazoles can be prepared from readily available starting materials in good to high yields with high efficiency
1-[2-(Trimethylsilyl)ethoxy]ethyl (SEE): A novel hybrid hydroxy-protecting group between 1-(ethoxy)ethyl (EE) and 2-(trimethylsilyl)ethoxymethyl (SEM)
作者:Junjun Wu、Brian K. Shull、Masato Koreeda
DOI:10.1016/0040-4039(96)00663-6
日期:1996.5
1-[(2-trimethylsilyl)ethoxy]ethyl (SEE) group, readily obtainable from an alcohol and 2-(trimethylsilyl)ethyl vinyl ether in the presence of a catalytic amount of PPTS, has been developed for the protection of hydroxyl groups. Its deprotection can be achieved under virtually neutral conditions with the use of a fluoride ion source, thus allowing for effective protection of hydroxyl groups of compounds that
An organocatalytic hydroalkoxylation/Claisen rearrangement/Michael addition tandem sequence: divergent synthesis of multi-substituted 2,3-dihydrofurans and 2,3-dihydropyrroles from cyanohydrins
作者:Zhen Sun、Zheng Li、Wei-Wei Liao
DOI:10.1039/c8gc03978j
日期:——
sequence is reported. The operational simplicity of the method allows for greater efficiency in the synthesis of a wide range of functionalized 2,3-dihydrofurans and 2,3-dihydropyrroles from readily accessible allylic cyanohydrins and activated alkynes in good to excellent yields under optimal conditions.