75730-13-1Relevant academic research and scientific papers
Synthesis and functionalization of 3-alkylidene-1,2-diazetidines using transition metal catalysis
Brown, Michael J.,Clarkson, Guy J.,Inglis, Graham G.,Shipman, Michael
, p. 1686 - 1689 (2011/05/06)
An efficient two-step synthesis of a wide range of 3-methylene-1,2- diazetidines has been developed through application of a Cu(I)-catalyzed 4-exo ring closure. The double bond of this new class of strained heterocycle can be functionalized in a stereocon
Chiral relay in NHC-mediated asymmetric β-lactam synthesis I; substituent effects in NHCs derived from (1R,2R)-cyclohexane-1,2-diamine
Duguet, Nicolas,Donaldson, Adele,Leckie, Stuart M.,Douglas, James,Shapland, Peter,Brown, Thomas B.,Churchill, Gwydion,Slawin, Alexandra M.Z.,Smith, Andrew D.
experimental part, p. 582 - 600 (2010/08/19)
The synthesis of a range of C2-symmetric imidazolinium salts from (1R,2R)-cyclohexane-1,2-diamine, and an evaluation of the reactivity and asymmetric induction of the derived NHCs as catalysts for the asymmetric synthesis of β-lactams, is reported. In this series, optimal enantioselectivity (up to 70% ee) is observed using N-benzyl or N-1-naphthylmethyl-substituted NHCs, consistent with a chiral relay effect operating to dictate the stereochemical outcome of this reaction.
Enantioselective reduction of α-substituted ketones mediated by the boronate ester TarB-NO2
Eagon, Scott,Ball-Jones, Nicholas,Haddenham, Dustin,Saavedra, Jaime,Delieto, Cassandra,Buckman, Matthew,Singaram, Bakthan
supporting information; experimental part, p. 6418 - 6421 (2010/12/30)
A facile and mild reduction procedure is reported for the preparation of chiral secondary alcohols prepared from α-substituted ketones using sodium borohydride and the chiral boronate ester (l)-TarB-NO2. Direct reduction of substituted ketones bearing Lewis basic heteroatoms generally provided secondary alcohols of only modest enantiomeric excess likely due to either competition between the target carbonyl and the functionalized sidechains at the Lewis acidic boron atom in TarB-NO2 or the added steric bulk of the α-sidechain. As an alternative method, these substrates were synthesized using TarB-NO2 via a two-step procedure involving the reduction of an α-halo ketone to a chiral terminal epoxide, followed by regioselective/regiospecific epoxide opening by various nucleophiles. This procedure provides access to a variety of functionalized secondary alcohols including β-hydroxy ethers, thioethers, nitriles, and amines with enantiomeric excesses of 94% and yields up to 98%.
Spiroborate esters in the borane-mediated asymmetric synthesis of pyridyl and related heterocyclic alcohols
Stepanenko, Viatcheslav,De Jesus, Melvin,Correa, Wildeliz,Guzman, Irisbel,Vazquez, Cindybeth,Ortiz, Lymaris,Ortiz-Marciales, Margarita
, p. 2738 - 2745 (2008/03/27)
The effectiveness of several spiroborate ester catalysts was investigated in the asymmetric borane reduction of 2-, 3-, and 4-acetylpyridines under different reaction conditions. Highly enantiomerically enriched 1-(2-, 3-, and 4-pyridyl)ethanols and 1-(heterocyclic)ethanols were obtained using 1-10% catalytic loads of the spiroborate 5 derived from diphenylprolinol and ethylene glycol.
Asymmetric allyl- and crotylboration with the robust, versatile, and recyclable 10-TMS-9-borabicyclo[3.3.2]decanes
Burgos, Carlos H.,Canales, Eda,Matos, Karl,Soderquist, John A.
, p. 8044 - 8049 (2007/10/03)
The remarkable versatility and selectivity of the 10-(trimethylsilyl)-9- borabicyclo[3.3.2]decanes (10-TMS-9-BBDs) in the allyl- and crotylboration of representative aldehydes are reported. The new reagents are prepared through air-stable crystalline pseudoephedrine borinic ester complexes of the 10-TMS-9-BBDs (4), which are available in 63% overall yield from B-MeO-9-BBN through a simple two-step procedure. These complexes 4 are directly converted to the corresponding B-allyl-10-TMS-9-BBDs (1) with allylmagnesium bromide, which either can be isolated (98%) or used in situ for the allylations. The remarkable enantioselectivity (96 to ≥99% ee) of these reagents in the rapid (3 h), asymmetric allylboration process at -78 °C is only slightly diminished when it is conducted at 25 °C, a phenomenon attributable to its rigid bicyclic structure. In addition to providing the homoallylic alcohols 6 efficiently (68-80%), the procedure also permits the efficient recovery of 4 (68-84%) for the direct regeneration of 1. Alternatively, an oxidative workup procedure can be used for the preparation of 6. The reagent gives predictable stereochemistry and exhibits an extremely high level of reagent control in the allylboration of D-glyceraldehyde acetonide. A simple and efficient procedure has been developed for the preparation of all four geometric and enantiomeric isomers of the B-crotyl-10-TMS-9-BBDs (10) from optically pure enantiomers of B-MeO-10-TMS-9-BBD (3). These reagents 10 also add rapidly (3 h) and efficiently to representative aldehydes at -78 °C, providing ready access to all four of the possible stereoisomers of the β-methyl homoallylic alcohols 12-15 (69-92%) in high dr (≥98:2) and ee (94-99%).
An efficient synthesis of tetrasubstituted cyclohexyl-1,2-diamines
Arjan, Hitesh,Boyd, Ewan,Coumbarides, Gregory S.,Eames, Jason,Jones, Ray V. H.,Stenson, Rachel A.,Suggate, Michael J.
, p. 1921 - 1925 (2007/10/03)
The synthesis of symmetrically tetrasubstituted diamines derived from the (R,R)-cyclohexyl-1,2-diamine is reported. We comment on the efficiency of this sequential substitution approach as a method for the synthesis of tetrasubstituted diamines and discus
New enantioselective chiral imidazolidine ligands for Pd-catalyzed asymmetric allylic alkylation
Lee, En-Kyung,Kim, Sang-Han,Jung,Ahn, Wha-Seung,Kim, Geon-Joong
, p. 1971 - 1974 (2007/10/03)
Chiral imidazolidine ligands have been synthesized from N,N′-dialkylated cyclohexanediamine derivatives and they were found to act as effective ligands in the palladium-catalyzed asymmetric allylic substitution. The excellent levels of enantiomeric excess up to 98% were obtained in high yield.
N,N'-dialkylated 1,2-diamine derivatives as new efficient ligands for RuCl2(PPh3)3 catalyzed asymmetric transfer hydrogenation of aromatic ketones
Kim, Geon-Joong,Kim, Sang-Han,Chong, Pong-Hyun,Kwon, Mi-Ae
, p. 8059 - 8062 (2007/10/03)
Chiral N,N'-dialkylated cyclohexanediamine derivatives ligands have been synthesized and used in an asymmetric transfer hydrogenation of aryl ketones. Optically active alcohols with up to 93% enantiomeric excess were obtained in high yield.
A practical and efficient synthesis of chiral N,N-disubstituted C2 symmetric diamines derived from (R,R)-1,2-diaminocyclohexane
Alexakis, Alexandre,Chauvin, Anne-Sophie,Stouvenel, Ricardo,Vrancken, Emmanuel,Mutti, Stephane,Mangeney, Pierre
, p. 1171 - 1178 (2007/10/03)
An improved synthesis of chiral diamine ligands derived from (R,R)-1,2-diaminocyclohexane is described, providing N-substituted diamines. The synthesis of other new ligands based on this methodology is also reported.
The asymmetric synthesis of α-substituted α-methyl and α-phenyl phosphonic acids: Design, carbanion geometry, reactivity and preparative aspects of chiral alkyl bicyclic phosphonamides
Bennani, Youssef L.,Hanessian, Stephen
, p. 13837 - 13866 (2007/10/03)
The design, preparation, structural and spectroscopic analyses of topologically unique and enantiomerically pure alkyl phosphonamides are described. In the case of α-ethyl and α-benzyl phosphonamides, the geometry of both the secondary and tertiary carbanions was determined to be planar through deprotonation/deuteration/alkylation experiments. Stereoselective alkylations of such systems proceeded in good yields and with high diastereoselectivities. The resulting α,α-alkylated phosphonamides were hydrolyzed to give the corresponding α,α-alkyl phosphonic acids with high degrees of enantiomeric purity.
