18937-82-1Relevant articles and documents
The synthesis of 2-alkylated cyclopentene-1,3-diones: Novel compounds with olfactory properties
Hailes, Helen C.,Isaac, Ben,Javaid, M. Hashim
, p. 29 - 41 (2003)
The syntheses of 2-butyl-4,5-dimethylcyclopent-4-ene-1,3-dione, possessing a buttery jasmine odor, and a series of analogues have been carried out via the synthesis of butenolactones, with subsequent conversion to 4,5-dimethylcyclopent-4-ene-1,3-dione and an alkylation strategy. The compound with the strongest odor characteristics, has also been synthesised using a Pauson-Khand reaction and selective oxidative route.
Mechanistic aspects on the formation of chiral allenes from propargylic ethers and organocopper reagents
Alexakis,Marek,Mangeney,Normant
, p. 8042 - 8047 (1990)
Propargylic ethers react with organocopper reagents to afford allenes by a syn addition to the triple bond followed by a β-elimination of the resulting alkenyl copper species. With use of chiral propargylic ethers and stoichiometric organocopper reagent, it was shown that the β-elimination step is purely anti, resulting in the formation of a chiral allene with 96% optical yield. The same reaction, run with a Grignard reagent RMgX and a catalytic amount of a Cu1 salt, affords allenes through an anti or syn overall process. The crucial step is the β-elimination of the intermediate alkenyl organometallic species, which is of anti type with RMgI and of syn type with RMgCl. Propargylic acetates, which also afford allenes in this reaction, but through a CuIII intermediate, are not sensitive to this "halogen effect".
Rhodium(III)-Catalyzed Directed C-H Dienylation of Anilides with Allenes Leads to Highly Conjugated Systems
Ghosh, Chiranjit,Nagtilak, Prajyot Jayadev,Kapur, Manmohan
supporting information, (2019/05/08)
Allenes are unique coupling partners in transition-metal-catalyzed C-H functionalization leading to a variety of products via alkenylation, allenylation, allylation, and annulation reactions. The outcome is governed by both the reactivity of the allene and the formation and stability of the organometallic intermediate. An efficient Rh(III)-catalyzed, weakly coordinating group-directed dienylation of electronically unbiased allenes is developed using an N-acyl amino acid as a ligand. Further elaboration of the dienylated products to construct polycyclic compounds is also described.
Palladium-catalyzed chemoselective allylic substitution, suzuki-miyaura cross-coupling, and allene formation of bifunctional 2-B(pin)-substituted allylic acetate derivatives
Kim, Byeong-Seon,Hussain, Mahmud M.,Hussain, Nusrah,Walsh, Patrick J.
supporting information, p. 11726 - 11739 (2014/10/15)
A formidable challenge at the forefront of organic synthesis is the control of chemoselectivity to enable the selective formation of diverse structural motifs from a readily available substrate class. Presented herein is a detailed study of chemoselectivity with palladium-based phosphane catalysts and readily available 2-B(pin)-substituted allylic acetates, benzoates, and carbonates. Depending on the choice of reagents, catalysts, and reaction conditions, 2-B(pin)-substituted allylic acetates and derivatives can be steered into one of three reaction manifolds: allylic substitution, Suzuki-Miyaura cross-coupling, or elimination to form allenes, all with excellent chemoselectivity. Studies on the chemoselectivity of Pd catalysts in their reactivity with boron-bearing allylic acetate derivatives led to the development of diverse and practical reactions with potential utility in synthetic organic chemistry.
Palladium-catalyzed formal hydroacylation of allenes employing acid chlorides and hydrosilanes
Fujihara, Tetsuaki,Tatsumi, Kenta,Terao, Jun,Tsuji, Yasushi
supporting information, p. 2286 - 2289 (2013/06/05)
The palladium-catalyzed formal hydroacylation of allenes employing acid chlorides and hydrosilanes has been achieved. The reactions proceed with commercially available Pd(OAc)2 as a catalyst and HSi(iPr) 3 as a reducing reagent, giving the corresponding α,β-unsaturated ketones regio- and stereoselectively.
Alkylidenesilacyclopropanes derived from allenes: Applications to the selective synthesis of triols and homoallylic alcohols
Buchner, Kay M.,Clark, Timothy B.,Loy, Janice M.N.,Nguyen, Thong X.,Woerpel
supporting information; experimental part, p. 2173 - 2175 (2009/10/24)
Several alkylidenesilacyclopropanes were prepared by silver-mediated silylene transfer to allenes. Oxasilacyclopentanes derived from allenes were prepared with high regio- and diastereoselectivity by a two-step, one-flask silacyclopropanation/carbonyl ins
Carbocupration/zinc carbenoid homologation and β-elimination reactions for a new synthesis of allenes - Application to the enantioselective synthesis of chiral allenes by deracemization of sp3-organometallic derivatives
Varghese, Jos P.,Zouev, Irena,Aufauvre, Lionel,Knochel, Paul,Marek, Ilan
, p. 4151 - 4158 (2007/10/03)
A new and straightforward carbocupration/zinc homologation/β-elimination reaction sequence allows the one-pot synthesis of polysubstituted allenes from acetylenic sulfoxides in excellent isolated chemical yields. Secondary zinc carbenoids were used for the homologation reaction, and so a new synthesis of 1,1-diiodoalkanes is described. This methodology also allows the synthesis of chiral allenes through thermodynamic equilibration of secondary organometallic derivatives. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2002.
Cyclization of acetylenic alkyllithiums
Bailey, William F.,Ovaska, Timo V.
, p. 3080 - 3090 (2007/10/02)
The scope and limitations of cyclization reactions involving acetylenic alkyllithiums, which were prepared at-78 °C by lithium-iodine exchange between the corresponding iodide and tert-butyllithium in a solution of n-pentane-diethyl ether (3:2 by volume), have been investigated. 4-Pentynyllithiums, 5-hexynyllithiums, and 6-heptynyllithiums bearing a phenyl or trimethylsilyl substituent on the triple bond undergo regiospecific exo-dig cyclization to give 4-, 5-, and 6-membered rings, respectively, bearing an exocyclic lithiomethylene moiety. Cyclization of the analogous alkyl-substituted acetylenic alkyllithiums seems to be confined to the 5-exo mode. The vinyllithium products of the cyclizations may be trapped by reaction with electrophiles to afford functionalized cycloalkylidene derivatives in good yield. The cyclization reactions were found to be highly stereoselective: intramolecular addition of the C-Li unit to the triple bond to produce 4- or 5-membered rings proceeds in a syn fashion to generate isomerically pure exocyclic vinyllithiums that may be functionalized to give stereoisomerically pure products. At the higher temperatures needed to effect cyclization of 6-heptynyllithiums, the initially formed (Z)-vinyllithium intermediate is isomerized to the more stable E-isomer which, when trapped with an electrophile, affords stereoisomerically pure product formally derived from anti addition to the triple bond.
INTRAMOLECULAR ADDITION OF ALKYLLITHIUMS TO ACETYLENES: REGIOSPECIFIC 4-, 5-, and 6-EXO-DIG CYCLIZATIONS
Bailey, William F.,Ovaska, Timo V.
, p. 627 - 630 (2007/10/02)
Primary acetylenic alkyllithiums bearing a phenyl substituent on the triple bond, which may be prepared in virtually quantitative yield by low-temperature lithium-iodine interchange, undergo regiospecific exo-dig cyclization via stereoselective syn-additi
