TEMPO-Mediated Aliphatic C–H Oxidation with Oximes and Hydrazones
摘要:
A method for aliphatic C-H bond oxidation of oximes and hydrazones mediated by 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) has been developed, which enables the concise assembly of substituted isoxazole and pyrazole skeletons.
Arylthio-Metal Exchange of α-Arylthioalkanenitriles
摘要:
The addition of BuLi, Bu3MgLi, Et2ZnBuLi, or Me2CuLi to alpha-arylthioalkanenitriles triggers an arylthio-metal exchange. NMR spectroscopic analyses implicate organometallic attack on sulfur forming a three-coordinate sulfidate as the key intermediate. Electrophilic trapping affords tertiary and quaternary nitriles in high yield. The method addresses the challenge of improving the functional group tolerance and preventing polyalkylations.
The reaction of thioacetals of phenyl ketones, α,α-bis(trimethylsilyl)alkyl sulfides, and 2-alkyl-2-ethylthioalkanenitriles with tributylstannyllithium gave the corresponding α-anions of sulfides, α,α-bis(trimethylsilyl)alkane, and nitriles, respectively.
Carbopalladation of Nitriles: Synthesis of Benzocyclic Ketones and Cyclopentenones via Pd-Catalyzed Cyclization of ω-(2-Iodoaryl)alkanenitriles and Related Compounds
作者:Alexandre A. Pletnev、Richard C. Larock
DOI:10.1021/jo0262006
日期:2002.12.1
An efficient procedure for the synthesis of 2,2-disubstituted benzocyclic ketones by intramolecular carbopalladation of nitriles has been developed. The cyclization of substituted 3-(2-iodoaryl)propanenitriles affords indanones in high yields. The reaction is compatible with a wide variety of functional groups. This methodology has been extended to the synthesis of tetralones and cyclopentenones.
Sulfone–Metal Exchange and Alkylation of Sulfonylnitriles
作者:Xun Yang、Dinesh Nath、Michael R. Gau、Omar W. Steward、Fraser F. Fleming
DOI:10.1002/anie.201704028
日期:2017.6.12
sulfone–metal exchange is described. Treating substituted 2‐pyridylsulfonylacetonitriles with either BuLi or Bu3MgLi generates metalated nitriles that efficiently intercept a variety of electrophiles to afford quaternary nitriles. The 2‐pyridylsulfone is critical for the sulfone–metal exchange because chelation anchors the organometallic proximal to the electrophilic, tetrasubstituted sulfone to override
描述了第一次一般的砜-金属交换。用BuLi或Bu 3 MgLi处理取代的2-吡啶基磺酰基乙腈会生成金属化的腈,该腈可有效拦截各种亲电试剂,从而生成季腈。2-吡啶基砜对于砜与金属的交换至关重要,因为螯合将有机金属锚定在亲电子的四取代砜的近端,以克服复合物引起的去质子化。用温和的碱(K 2 CO 3或DBU)烷基化2-吡啶磺酰基乙腈,然后进行砜-金属交换和烷基化,通过三个烷基化作用快速组装季腈,其中只有一个需要有机金属试剂。
Chemoselective Alkylations with <i>N</i>- and <i>C</i>-Metalated Nitriles
作者:Xun Yang、Dinesh Nath、Fraser F. Fleming
DOI:10.1021/acs.orglett.5b02481
日期:2015.10.2
electrophilic alkylations. N-Lithiated or C-magnesiated nitriles can be prepared from the same nitrile precursor and selectively reacted with a 1:1 mixture of methyl cyanoformate and benzyl bromide or bifunctionalelectrophiles through chemoselective attack onto either an alkyl halide or a carbonyl electrophile. A mechanistic explanation for the chemoselectivity preferences is provided that rests on the structural
organolithiums, Grignardreagents, or zincates to sulfinylnitriles triggers a facile sulfinyl–metal exchange to afford N‐ or C‐metalated nitriles. Sulfinyl–magnesium exchange–alkylations efficiently install quaternary and tertiary centers, even in the case of tertiary sulfinylnitriles that contain a highly acidic methine proton. α‐Sulfinylalkenenitriles afford moderately nucleophilic magnesiated nitriles, and