A New Variant of the Mannich Reaction

Kinast, Günther; Tietze, L. F.

doi:10.1002/anie.197602391

Cited by 114 publications

(41 citation statements)

References 8 publications

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“…Mannich type reaction 13 of 10 with Eschenmoser-chloride 14 followed by deprotection with hydrochloric acid in tetrahydrofuran leads to a-methylene dialdehydes 1 in 55% to 65% yield.…”

Section: Preparation Of Starting Materialsmentioning

confidence: 99%

Intramolecular Chromium(II)-Catalyzed Pinacol Cross Coupling of 2-Methylene-α,ω-dicarbonyls

Groth

Jung²,

Vogel³

2004

Synlett

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Using only 10% of CrCl 2 as catalyst, manganese-powder as reducing agent and TMSCl as scavenger, 2-methylene-a,w-dialdehydes and -ketones can be coupled to form cyclic diols diastereoselectively. The diastereomeric excess strongly depends on the ring size and the substituents of the w-carbonyl group. The greater the ring size the higher diastereoselectivities are observed. In all cases cis-diols are preferentially formed.

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“…Mannich type reaction 13 of 10 with Eschenmoser-chloride 14 followed by deprotection with hydrochloric acid in tetrahydrofuran leads to a-methylene dialdehydes 1 in 55% to 65% yield.…”

Section: Preparation Of Starting Materialsmentioning

confidence: 99%

Intramolecular Chromium(II)-Catalyzed Pinacol Cross Coupling of 2-Methylene-α,ω-dicarbonyls

Groth

Jung²,

Vogel³

2004

Synlett

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“…Compound B 1.291 (8) C(C 1 )-C-N 1.5 13 (7) C(C2)-C-N 1.5 15 (7) C(C1)-C-C(C2) 1.505 (7) C-N-C(N 1) 1.509 (7) C…”

Section: Cation Disordermentioning

confidence: 99%

“…A recent search of the Cambridge Structural Database using a novel search procedure (54) has uncovered further examples of N-H.. .IT bonds, often unnoticed by the original authors. In Part 4 of this series (see footnote 8) we shall report on numerous additional examples of N-H.. .IT bonding in tetraphenylborate structures and provide a detailed discussion of the geometric scope of such bonding.…”

Section: Acknowledgmentsmentioning

confidence: 99%

Crystal chemistry of tetraradial species. Part 3. Salts of aliphatic Schiff bases crystallizable from aqueous media: crystal structures of five iminium tetraphenylborates and a 6-31G* ab initio study of simple iminium ions

Knop¹,

Cameron²,

Bakshi³

et al. 1993

Can. J. Chem.

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. Recrystallization of a primary or secondary alkylammonium tetraphenylborate (TB) from approximately 1 : 1 mixtures of Me2C0 (or MeEtCO) and water yields, against expectation, the TB of the corresponding iminium cation and thus provides an easy route to a variety of aliphatic Schiff bases. The crystal structures of five such salts have been de- are discussed in detail, as also is the tendency of the small iminium ions to orientational disorder. The range of the C=N bond length in these and other iminium salts is quite narrow, with 1.283(12) A as the mean (uncorrected) value. Where a hydrogen atom(s) is attached to the iminium nitrogen, it will form a hydrogen bond (simple or bifurcated) with the aromatic n system of the nearest phenyl ring(s). The narrowness of the C=N bond-length range with respect to substitution on the cation has prompted a detailed 6-31G" ab ir~itio study of the effect, on the geometry of the [H,c=NH,]+ ion, of a partial or complete replacement of the H atoms by one of the following substituents: F, C1, CN, Li, and Na. The 46 structures optimized in planar geometry were supplemented by a number of optimizations of similarly substituted ethylenes as well as by a few optimizations in perpendicular geometry. Analysis of the numerical results involves the bond lengths and angles, Mulliken EM and (in part) Lijwdin EL net charges on the atoms, and electron densities p, = p(r,) at the bond critical points. Only a limited use has been made of comparisons involving the total electronic energies E (substitutional isomerism). Since the above substituents span the entire electronegativity scale, and CN provides for the possibility of conjugation, the effects they produce are expected to bracket the effects that would be produced by any other substituents. The calculations confirm the essential narrowness of the C=N bond-length range in iminium ions. They also show that, at least in the 6-31G:!: scheme, the nitrogen in [H'C=NH,]+ carries a significant negative net charge (both in terms of EM and e,), which is contrary to the conventional representation of the ion as H2C=N+H2. The trends observed in the parameters are smooth and highly self-consistent except for the tri-and tetrasubstituted ions containing Li or Na, where interligand repulsions may invalidate the assumption of planarity. Many of the parameters can be represented to a high degree of correlation as linear functions a, + actzc(X) + aNtl,(X) of the numbers tz of substituent atoms X on the C and N atoms. This representation makes it possible to estimate the contribution to the parameter value from the substitution at the distant atom of the C=N bond, i.e., the extent of localization of the effect produced by the substituent. The success of the linearization of the parameter variation raises the important question of whether the apparent additivity is genuine and intrinsic or merely a property of the 6-31G:': optimization scheme. In other words, will additivity be retained, functionally, for sets of parameters obtained from higher level ab ini...

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“…Some important experimental modifications involve the use of preformed iminium salts [5][6][7][8][9] , which can be prepared by a number of methods including the reactions of acetyl chloride with aminals 10 , of trifluoroacetic anhydride with N-oxides 11 , and of trichloromethylsilane with aminol ethers 12 .…”

Section: Introductionmentioning

confidence: 99%

A novel one pot Mannich synthesis of methylpiperidin phenols, methylphenylmorfolin phenols and methyltiophenylmorpholin phenols solvent-free and using infrared light irradiation

Velázquez¹,

Torres²,

Díaz³

et al. 2006

Arkivoc

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A New Variant of the Mannich Reaction

Cited by 114 publications

References 8 publications

Intramolecular Chromium(II)-Catalyzed Pinacol Cross Coupling of 2-Methylene-α,ω-dicarbonyls

Intramolecular Chromium(II)-Catalyzed Pinacol Cross Coupling of 2-Methylene-α,ω-dicarbonyls

Crystal chemistry of tetraradial species. Part 3. Salts of aliphatic Schiff bases crystallizable from aqueous media: crystal structures of five iminium tetraphenylborates and a 6-31G* ab initio study of simple iminium ions

A novel one pot Mannich synthesis of methylpiperidin phenols, methylphenylmorfolin phenols and methyltiophenylmorpholin phenols solvent-free and using infrared light irradiation

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