- Inexpensive multigram-scale synthesis of cyclic enamines and 3-N spirocyclopropyl systems
-
Cyclic enamines are important synthons for many synthetic and pharmacological targets. Here, we report an inexpensive, catalyst-free, multigram-scale synthesis for cyclic enamines with exocyclic double bonds and four- to seven-membered rings. This strategy is more conducive to scale up, permissive of functionalization around the cyclic system, and less sensitive to the nature of the N-protecting group than previously-described methods for cyclic enamine synthesis. Further, we explore application of these enamines to the synthesis of highly-strained spirocyclic 3N-cyclopropyl scaffolds.
- Kumar, Pratik,Zainul, Omar,Laughlin, Scott T.
-
supporting information
p. 652 - 656
(2018/02/07)
-
- Gold-catalysed oxyarylation of styrenes and mono- and gem-disubstituted olefins facilitated by an iodine(III) oxidant
-
1-Hydroxy-1,2-benziodoxol-3(1H)-one (IBA) is an efficient terminal oxidant for gold-catalysed, three-component oxyarylation reactions. The use of this iodine(III) reagent expands the scope of oxyarylation to include styrenes and gem-disubstituted olefins, substrates that are incompatible with the previously reported Selectfluor-based methodology. Diverse arylsilane coupling partners can be employed, and in benzotrifluoride, homocoupling is substantially reduced. In addition, the IBA-derived co-products can be recovered and recycled. The I's have it: The unprecedented use of an iodine(III) reagent as the terminal oxidant for gold-catalysed oxyarylation allows the substrate scope to be significantly expanded; in addition to monosubstituted olefins, styrenes and gem-disubstituted olefins are well tolerated (see scheme). With benzotrifluoride as solvent, unproductive homodimerisation of the arylsilane coupling partner is effectively suppressed. Copyright
- Ball, Liam T.,Lloyd-Jones, Guy C.,Russell, Christopher A.
-
supporting information; experimental part
p. 2931 - 2937
(2012/04/23)
-
- Chiral aminophosphines as catalysts for enantioselective double-michael indoline syntheses
-
The bisphosphine-catalyzed double-Michael addition of dinucleophiles to electron-deficient acetylenes is an efficient process for the synthesis of many nitrogencontaining heterocycles. Because the resulting heterocycles contain at least one stereogenic center, this double-Michael reaction would be even more useful if an asymmetric variant of the reaction were to be developed. Aminophosphines can also facilitate the double-Michael reaction and chiral amines are more readily available in Nature and synthetically; therefore, in this study we prepared several new chiral aminophosphines. When employed in the asymmetric double-Michael reaction between ortho-tosylamidophenyl malonate and 3-butyn-2-one, the chiral aminophosphines produced indolines in excellent yields with moderate asymmetric induction.
- Khong, San N.,Kwon, Ohyun
-
p. 5626 - 5650
(2012/07/03)
-
- Palladium(II)-N-heterocyclic carbene complexes derived from proline: Synthesis and characterization
-
Pd(II)-N-heterocyclic carbene complexes derived from proline have been successfully synthesized in good yields and their structures have been characterized by X-ray single crystal diffraction. It was found that the substituents on the N-atom of the pyrrolidine skeleton dramatically affect on the coordination pattern of the palladium complexes. In a word, when an electron-rich group as benzyl group was attached on the N-atom, both of the N-atom and NHC were coordinated to the Pd(II) center; while when an electron-poor group as Ts group was attached, a dimeric mono-coordinated Pd(II)-NHC was obtained exclusively.
- Tang, Yi-Qiang,Lu, Jian-Mei,Wang, Xiu-Ren,Shao, Li-Xiong
-
experimental part
p. 7970 - 7974
(2010/10/19)
-
- Oxidative desulfurization-fluorination of thioethers. Application for the synthesis of fluorinated nitrogen containing building blocks
-
An oxidative desulfurization-fluorination protocol has been used to synthesize (2S)-2-(difluoromethyl)-N-tosylpyrrolidine (6a) and (2S)-2-(trifluoromethyl)-N-tosylpyrrolidine (7a) from the (2S)-prolinol-derived (2S)-2-(4-chlorophenylthiomethyl)-N-tosylpyr
- Hugenberg, Verena,Froehlich, Roland,Haufe, Guenter
-
experimental part
p. 5682 - 5691
(2011/02/18)
-
- Synthesis of new [(2S)-N-(p-Tolylsulfonyl)-2-Pyrrolidinyl]Propyl 2,3,4-Tri-O-Acetyl- and 2,3,4-Tri-O-Benzyl-β-L-Fucopyranosides
-
Synthesis of two new glycoheterocyclic compounds, [(2S)-N-(p-tolylsulfonyl) -2-pyrrolidinyl]propyl 2,3,4-tri-O-acetyl- and 2,3,4-tri-O-benzyl-β-L- fucopyranosides la and lb, starting from δ-amino alcohol (-)-[(2S)-N-(ptolylsulfonyl)-2-pyrrolidinyl]propan-l-ol 2 and O-α-L-fucosyltrichloroacetimidates 3a or 3b as glycosyl donor is described. Hitherto δ-aminoalcohol 2 was synthesized from L-proline without any racemization during its preparation.
- E Silva, Maria Joselice,Srivastava, Rajendra M.,Doboszewski, Bogdan,Cottier, Louis,Sinou, Denis
-
p. 105 - 111
(2011/06/26)
-
- Total synthesis and identification of two diastereoisomers of 1-methyl-2-[N-(p-tolylsulfonyl)-2-pyrrolidinyl]ethyl β-L-fucopyranoside
-
The reaction of a racemic mixture of (2R,2′S)- and (2S,2′R)-N-(p-tolylsulfonyl)-2-pyrrolidinyl-2-propanol, prepared from (S)-proline, with 2,3,4-tri-O-acetyl-α-l-fucopyranosyl trichloroacetimidate led to both diastereoisomers of the title compound after O-deacetylation.
- E Silva, Maria Joselice,Cottier, Louis,Srivastava, Rajendra M.,Sinou, Denis,Thozet, Alain
-
p. 309 - 314
(2007/10/03)
-
- Asymmetric Synthesis. Metal Complex Mediated Synthesis of Chiral Glycine by Enantioselective Proton Exchange
-
The complex (1+), a species containing a chiral tridentate triamine ligand, (S,S)-proam, and a tridentate ligand incorporating a glycine residue, picgly, has been prepared.The α-protons of the coordinated glycine residue exchange at different rates in basic D2O solutions.The difference in rate was found to be 7.8:1 in favor of the pro-S proton at pD 11.2 at 25 deg C with a NaHCO3/Na2CO3 buffer.It is proposed that the origins of this enantiosection arise from both steric and hydrogen-bonding effects as inferred from the determined crystal structure of the complex.A kinetic analysis of the exchange process shows that the system is essentially that of an asymmetric synthesis (CH2 -> CHD) followed by a reinforced kinetic resolution (CHD -> CD2).As such, the optical purity of the chiral glycine (NH2CHDCO2H) continuously increases with the extent of reaction.This was confirmed.It is suggested that the present kinetic relationships are representative of the majority of asymmetric syntheses involving enantiotopic atoms or groups, and it follows that, for such systems, quoting an enantiomeric excess has meaning only when the extent of reaction is specified.
- Dokuzovic, Zdravko,Roberts, Nicholas K.,Sawyer, Jeffery F.,Whelan, John,Bosnich, B.
-
p. 2034 - 2039
(2007/10/02)
-