- Hexafluoroisopropanol: A powerful solvent for the hydrogenation of indole derivatives. Selective access to tetrahydroindoles or cis-fused octahydroindoles
-
Pd/C in HFIP was used to hydrogenate indole derivatives under relatively mild conditions, leading to potential synthetic intermediates of bioactive compounds. Depending on their substitution, tetrahydroindoles or octahydroindoles could selectively be obtained.
- Clarisse, Damien,Fenet, Bernard,Fache, Fabienne
-
experimental part
p. 6587 - 6594
(2012/09/08)
-
- Tandem Zinc Mediated Reductive Cleavage-Reductive Amination as a New Approach to Substituted Pyrrolidines from Homoallylic Amines
-
N-Boc or N-Cbz homoallylic amines are converted in four steps into pyrrolidines through a sequence involving as a key-step a tandem zinc mediated reductive amination from an intermediate 1,3-oxazin-2-one
- Vanucci, Corinne,Brusson, Xavier,Verdel, Valerie,Zana, Frederique,Dhomane, Hamid,Lhommet, Gerard
-
p. 2971 - 2974
(2007/10/02)
-
- A Stereoselective Synthesis of (+/-)-trans-Cycloalkanopiperidines and Cycloalkanopyrrolidines via Hydroboration
-
A highly stereoselective synthesis of trans-cycloalkanopiperidines and cycloalkanopyrrolidines has been achieved via hydroboration of bromocycloalkenes with dichloroboranes.The intermediate bromocycloalkylboronic acids were converted into azidocycloalkylboronates.Addition of two equivalents of boron trichloride in dichloromethane generated dichloroboranes which, by an intramolecular cyclisation gave intermediates 11.These can be readily hydrolyzed to get the corresponding important nitrogen heterocycles in good yields and excellent stereochemical purities.
- Brown, Herbert C.,Salunkhe, Ashok M.
-
p. 1265 - 1268
(2007/10/02)
-
- Azabicyclo Chemistry. 7. Ultra-High Field (600 MHz) NMR Spectroscopy in Solving Conformational Problems: cis-Octahydroindoles
-
Studies using ultra-high field (600 MHz) nmr spectroscopy has allowed us to assign the conformational preference of cis-octahydroindoles, including the position of their nitrogen lone-pair electrons.Lithium aluminium hydride reduction of cis-octahydroindol-2-one (4) gave cis-octahydroindole (5a) which showed three distinct nmr resonances, the C7a proton at δ 3.04 (apparent q, J = 5.3 Hz) and the two C2 protons at δ 3.10 and 2.94.The latter two resonances were absent in the C2 deuterated compound 5b.Deuteromethylation of 5a, via a urethane intermediate, gave 1-deuteromethyl-cis-octahydroindole (8a) which showed resonances at δ 3.12 for the α-faced C2 proton, the β-faced C2 proton at δ 2.17, and the C7a proton at δ 2.15.The resonances at δ 3.12 and 2.17 are absent in the corresponding C2 deuterated compound 8b, and the C7a remains as a doublet of triplets (d, J = 5.5 Hz; t, J = 3.8 Hz).Interpretation of the above data led us to assign 8a as the cis compound with nitrogen axial, and the lone pair electrons in a pseudo-axial position and antiperiplanar to the C7a and β-faced C2 protons.The amine 5a is also cis and has the nitrogen axial, but the lone pair electrons are pseudo-equatorial.Inspection of the Bohlmann band region in the ir of 5a and 8a supports the above assignments.These investigations thus suggest, in cis-octahydroindoles, the following steric order: methyl > lone pair > H.
- Mokotoff, Michael,Hill, Scott T.
-
-
- DIASTEREOSELECTIVE SYNTHESIS OF BICYCLIC AMINO ACIDS VIA RING CONTRACTION OF α-CHLOROLACTAMS
-
Bicyclic lactams were converted to their α-chloro-derivatives and subjected to ring contraction under basic conditions to give bicyclic acids in diasteroselective fashion.
- Henning, R.,Urbach, H.
-
p. 5339 - 5342
(2007/10/02)
-