- Reaction of lithium diethylamide with an alkyl bromide and alkyl benzenesulfonate: Origins of alkylation, elimination, and sulfonation
-
A combination of NMR, kinetic, and computational methods are used to examine reactions of lithium diethylamide in tetrahydrofuran (THF) with n-dodecyl bromide and n-octyl benzenesulfonate. The alkyl bromide undergoes competitive SN2 substitution and E2 elimination in proportions independent of all concentrations except for a minor medium effect. Rate studies show that both reactions occur via trisolvated-monomer-based transition structures. The alkyl benzenesulfonate undergoes competitive SN2 substitution (minor) and N-sulfonation (major) with N-sulfonation promoted at low THF concentrations. The SN2 substitution is shown to proceed via a disolvated monomer suggested computationally to involve a cyclic transition structure. The dominant N-sulfonation follows a disolvated-dimer-based transition structure suggested computationally to be a bicyclo[3.1.1] form. The differing THF and lithium diethylamide orders for the two reactions explain the observed concentration-dependent chemoselectivities.
- Gupta, Lekha,Ramirez, Antonio,Collum, David B.
-
supporting information; experimental part
p. 8392 - 8399
(2011/03/20)
-
- Joint Synthesis of Tertiary Unsymmetrical and Symmetrical Aliphatic Amines
-
Tertiary unsymmetrical and symmetrical aliphatic amines were prepared by reaction of higher (C8-C16) and lower (C2-C4) aliphatic alcohols with nitriles containing the same number of carbon atoms as the lower aliphatic alcohols. Reaction conditions ensuring nearly quantitative yields of tertiary amines were determined.
- Kozlov,Tereshko,Basalaeva,Tarasevich
-
p. 1095 - 1098
(2007/10/03)
-
- Aminoborohydrides as Reducing Agents. 1. Sodium (Dimethylamino)- and (tert-Butylamino)borohydrides as Selective Reducing Agents
-
Replacement of a hydride in borohydride by an electron-donating alkylamino group greatly enhances the reducing ability of the resulting reagents.Thus, sodium (dimethylamino)- and (tert-butylamino)borohydrides (1, NaDMAB, and 2, NaTBAB, respectively) not only reduce aldehydes and ketones to alcohols but also are effective for the conversion of esters to alcohols and primary amides to amines in good to excellent yields.Tertiary amides are reduced to alcohols (i.e., N,N-dimethylamides) or amines (i.e.N,N-diisopropylamides) depending on the steric bulk of the alkyl substituents on nitrogen.However, secondary amides are not reduced by the reagents allowing selective conversion of primary and tertiary amides in the presence of secondary amides.Nitriles are attacked by the reagents but do not afford synthetically useful amounts of amine products.Aryl halides are slowly converted to arenes, but alkyl halides and epoxides undergo unusual reactions with the amino portion of the reagents.
- Hutchins, Robert O.,Learn, Keith,El-Telbany, Farag,Stercho, Yuriy P.
-
p. 2438 - 2443
(2007/10/02)
-