α-Diazo-β-ketonitriles: uniquely reactive substrates for arene and alkene cyclopropanation.
نویسندگان
چکیده
An investigation of the intramolecular cyclopropanation reactions of α-diazo-β-ketonitriles is reported. These studies reveal that α-diazo-β-ketonitriles exhibit unique reactivity in their ability to undergo arene cyclopropanation reactions; other similar acceptor-acceptor-substituted diazo substrates instead produce mixtures of C-H insertion and dimerization products. α-Diazo-β-ketonitriles also undergo highly efficient intramolecular cyclopropanation of tri- and tetrasubstituted alkenes. In addition, the α-cyano-α-ketocyclopropane products are demonstrated to serve as substrates for SN2, SN2', and aldehyde cycloaddition reactions.
منابع مشابه
Ruthenium-catalyzed intramolecular cyclization of diazo-β-ketoanilides for the synthesis of 3-alkylideneoxindoles.
With [Ru(p-cymene)Cl(2)](2) as catalyst, diazo-β-ketoanilides would undergo intramolecular carbenoid arene C-H bond functionalization to afford 3-alkylideneoxindoles in up to 92% yields. The reaction occurs under mild conditions and exhibits excellent chemoselectivity. The lack of primary KIE (k(H)/k(D) ~ 1) suggests that the reaction should not proceed by rate-limiting C-H bond cleavage; a mec...
متن کاملDiastereoselective Radical‐Type Cyclopropanation of Electron‐Deficient Alkenes Mediated by the Highly Active Cobalt(II) Tetramethyltetraaza[14]annulene Catalyst
A new protocol for the catalytic synthesis of cyclopropanes using electron-deficient alkenes is presented, which is catalysed by a series of affordable, easy to synthesise and highly active substituted cobalt(II) tetraaza[14]annulenes. These catalysts are compatible with the use of sodium tosylhydrazone salts as precursors to diazo compounds in one-pot catalytic transformations to afford the de...
متن کاملHighly Enantio- and Diastereoselective Construction of 1,2-Disubstituted Cyclopentane Compounds by Dirhodium(II) Tetrakis[N-phthaloyl-(S)-tert-leucinate]-Catalyzed C‒H Insertion Reactions of α-Diazo Esters
A highly enantioand diastereoselective intramolecular C–H insertion reaction of α-diazo esters has been achieved with the use of dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate] as a catalyst, providing exclusively cis-2-arylcyclopentane-1-carboxylates in up to 95% ee with no evidence of alkene formation.
متن کاملSynthesis of Polycyclic Ring Systems Using Transition Metal Catalyzed Cyclizations of Diazo Alkynyl Ketones
Abstract: The rhodium(II)-catalyzed reaction of α-diazo ketones bearing tethered alkyne units represents a new and useful method for the construction of a variety of substituted cyclopentenones. The process proceeds by addition of the rhodium-stabilized carbenoid onto the acetylenic π-bond to give a vinyl carbenoid intermediate. The resulting rhodium complex undergoes a wide assortment of react...
متن کاملNickel(ii)-catalyzed enantioselective cyclopropanation of 3-alkenyl-oxindoles with phenyliodonium ylide via free carbene† †Electronic supplementary information (ESI) available. CCDC 1038443 and 1038445. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc03658e Click here for additional data file. Click here for additional data file.
The catalytic asymmetric cyclopropanation of a C]C double bond provides efficient access to optically active cyclopropane derivatives that are essential motifs in natural products and valuable building blocks for various transformations. Chiral transition-metal-catalyzed carbene transfer, such as that using Cu(I)-, Rh(II)-, Ru(II)-, and Co(II)-complexes with diazo compounds, permits such cylcop...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of the American Chemical Society
دوره 135 19 شماره
صفحات -
تاریخ انتشار 2013