Trialkylamines More Planar at Nitrogen Than Triisopropylamine in the Solid State
摘要:
A short synthesis of exceedingly congested amines, with insertion of a rhodium carbenoid into an N-H bond as the key step, is described. Trialkylamines such as 2-(diisopropylamino)propane-1,3-diol (8) and 2-(2,2,6,6-tetramethyl-1-piperidinyl)propane-1,3-diol (10) may be prepared easily. Examination of amines of this type by X-ray crystallography reveals nearly planar nitrogens. Indeed, they are all more planar than the nitrogen of triisopropylamine, which had long been thought to be perfectly planar, but which is in fact very slightly pyramidal. The distance (h) of the nitrogen of triisopropylamine to the plane defined by the three carbons to which it is bonded is 0.28-0.29 angstrom. In 8, by comparison, h is 0.185 angstrom. A qualitative orbital interaction explanation is proposed to rationalize the tendency of nitrogen to planarize when attached to the 1,3-dihydroxy-2-propyl group. Cyclic voltammetric measurements of nitrogen one-electron oxidation of the nearly planar trialkylamines revealed no correlation between E-1/2(ox) and degree of planarity.
dimethyl diazomalonate has been found to insert into the N-H bond of sterically hindered secondary aliphaticamines to afford hinderedtertiaryaliphaticamines in quite satisfactory yields. For example dimethyl 2-(dicyclohexylamino)propanedioate was formed in 85% yield from dicyclohexylamine, and the severely hindered dimethyl 2-(2,2,6,6-tetramethyl-1-piperidinyl)propanedioate was formed in 38% yield
Trialkylamines More Planar at Nitrogen Than Triisopropylamine in the Solid State
作者:Minmin Yang、Thomas Albrecht-Schmitt、Vince Cammarata、Peter Livant、David S. Makhanu、Richard Sykora、Wei Zhu
DOI:10.1021/jo802086h
日期:2009.4.3
A short synthesis of exceedingly congested amines, with insertion of a rhodium carbenoid into an N-H bond as the key step, is described. Trialkylamines such as 2-(diisopropylamino)propane-1,3-diol (8) and 2-(2,2,6,6-tetramethyl-1-piperidinyl)propane-1,3-diol (10) may be prepared easily. Examination of amines of this type by X-ray crystallography reveals nearly planar nitrogens. Indeed, they are all more planar than the nitrogen of triisopropylamine, which had long been thought to be perfectly planar, but which is in fact very slightly pyramidal. The distance (h) of the nitrogen of triisopropylamine to the plane defined by the three carbons to which it is bonded is 0.28-0.29 angstrom. In 8, by comparison, h is 0.185 angstrom. A qualitative orbital interaction explanation is proposed to rationalize the tendency of nitrogen to planarize when attached to the 1,3-dihydroxy-2-propyl group. Cyclic voltammetric measurements of nitrogen one-electron oxidation of the nearly planar trialkylamines revealed no correlation between E-1/2(ox) and degree of planarity.
General Ir-Catalyzed N–H Insertions of Diazomalonates into Aliphatic and Aromatic Amines
作者:Zhuang Zhong、Céline Besnard、Jérôme Lacour
DOI:10.1021/acs.orglett.3c03929
日期:2024.2.9
reactivity of acceptor–acceptor diazo malonate reagents is reported using [Ir(cod)Cl]2 as catalyst. A large range of amines, primary and secondary, aliphatic and aromatic, is possible. Mild temperatures, perfect substrate/reactant stoichiometry, and good functional group compatibility render the process particularly attractive for the (late-stage) functionalization of amines.