Reinvestigation of the grignard reactions with formic acid. A convenient method for preparation of aldehydes

Grignard reagents react with formic acid in tetrahydrofuran to produce aldehydes in relatively good yields Various aldehydes such as alkyl, aryl, allyl, benzyl and vinyl aldehydes were prepared from the corresponding Grignard reagents. The reaction with vinyl Grignard reagents proceeded with retention of configuration.     

Addition of a chiral copper reagent derived from propargylic oxazolidininone to aldehydes

[reaction: see text] The copper reagent arising from an optically pure propargylic oxazolidinone was found to react regio- and diastereoselectively with aldehydes, leading, in a one-pot procedure, to the anti homopropargylic amino alcohols derivatives in good yields.     

Silafunctional compounds in organic synthesis. 27. (Isopropoxydimethylsilyl)methyl grignard reagent: A new nucleophilic hydroxymethylating agent for aldehydes and ketones

Nucleophilic hydroxymethylation of aldehydes and ketones has been achieved by the reaction with the (isopropoxydimethylsilyl)methyl Grignard reagent and the subsequent oxidative cleavage of the carbon-silicon bond.     

一种高效、洁净的还原醛的新方法

报道了在超临界CO2中，实现氢转移反应的新方法，这一方法以水为氢授体， 锌粉为电子授体，高选择性地还原对甲基苯甲醛为相应的醇，并初步研究了反应温 度、反应体系中CO2的压力、反应时间对还原反应的转化率的影响。     

A novel three carbon-amino grignard reagent: its use in an efficient pyrrolidine synthesis

A novel primary amino protected Grignard reagent has been developed; 2,2,5,5-tetramethyl-1-aza-2,5-disilacyclopentane-1-propyl magnesium bromide 1a. Its usefulness is illustrated in the synthesis of 2-substituted pyrrolidines.     

A stereoselective reducing agent derived from a nitrogen-containing polymer deposited on a carbon support

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2875–2876, December, 1990.     

Chemoselective Schmidt reaction mediated by triflic acid: selective synthesis of nitriles from aldehydes

An excellent utility of Schmidt reaction of aldehydes to access corresponding nitriles in an instantaneous reaction is demonstrated. The reaction of aldehydes with NaN(3) and TfOH furnishes the corresponding nitriles in near quantitative yields and tolerates a variety of electron-withdrawing and electron-donating substituents on the substrates. Formanilides, a common side product in Schmidt reaction, is not observed in this reaction. Besides these advantages, the salient feature of this reaction is that it exhibits a remarkable chemoselectivity, as acid and ketone functionalities are well tolerated under the reaction conditions. The reaction is easily scalable, high yielding, and nearly instantaneous.     

Borohydride reducing agent derived from anion exchange resin: selective reduction of α, β-unsaturated carbonyl compounds.

Borohydride exchange resin (BER) exhibited selectivity in the reduction of α, β-unsaturated carbonyl compounds to the corresponding unsaturated alcohols.     

Reactions of pyridyl and quinolyl sulfoxides with grignard reagent: A convenient preparation of pyridyl and quinolyl grignard reagents

3-,4-Pyridyl and 4-quinolyl Grignard reagents were generated by the reaction of the corresponding phenyl sulfoxides with PhMgBr and give the adducts upon treatment with various aldehydes and ketones. The stereochemistry for the reaction was investigated.     

Formylation of organometallic compounds with lithium (or sodium) formate. Part I. A facile synthesis of aldehydes from grignard reagent

Grignard reagent reacts with lithium (or sodium) formate in boiling THF giving the corresponding aldehydes in good yields. This reaction can be carried out at room temperature as well, but stirring of the reaction mixture for two or three days is required.     

Formic acid reduction—XVII : Kinetic studies on the formic acid reduction of N-benzylideneaniline

The formic acid reduction of azomethine which has been reported² to proceed nearly quantitatively by the use of the formate reagent, 5HCO₂H·2NEt₃, was kinetically investigated by the carbon dioxide trapping and UV spectroscopic methods, using N-benzylideneaniline as a representative. Rate data gave the rate equation, v = (k + k′ [NEt₃])[N-benzylideneaniline][HCO₂H], indicating two-path mechanism. By the technique of using deuterated formic acids, it was found that the hydrogen bound to the carbon of formic acid is transferred as hydride to the carbon of the CN double bond in the rate determining step. The reaction is facilitated by the electron-releasing substituents of the two benzene rings of N-benzylideneaniline. On the bases of these results a possible mechanism is proposed.     

Kinetic study on disproportionations of C1 aldehydes in supercritical water: methanol from formaldehyde and formic acid

The reaction pathways and kinetics of C1 aldehydes, formaldehyde (HCHO) and formic acid (HCOOH=HOCHO), are studied at 400 degrees C in neat condition and in supercritical water over a wide range of water density, 0.1-0.6 g/cm3. Formaldehyde exhibits four reactions: (i) the self-disproportionation of formaldehyde generating methanol and formic acid, (ii) the cross-disproportionation between formaldehyde and formic acid generating methanol and carbon dioxide, (iii) the water-independent self-disproportionation of formaldehyde generating methanol and carbon monoxide, and (iv) the decarbonylation of formaldehyde generating hydrogen and carbon monoxide. The self- and cross-disproportionations overwhelm the water-independent self-disproportionation and the formaldehyde decarbonylation. The rate constants of the self- and cross-disproportionations are determined in the water density range of 0.1-0.6 g/cm3. The rate constant of the cross-disproportionation is 2-3 orders of magnitude larger than that of the self-disproportionation, which indicates that formic acid is a stronger reductant than formaldehyde. Combining the kinetic results with our former computational study on the equilibrium constants of the self- and cross-disproportionations, the reaction mechanisms of these disproportionations are discussed within the framework of transition-state theory. The reaction path for methanol production can be controlled by tuning the water density and reactant concentrations. The methanol yield of approximately 80% is achieved by mixing formaldehyde with formic acid in the ratio of 1:2 at the water density of 0.4 g/cm3.     

Hydrothermal carbon-carbon bond formation and disproportionations of C1 aldehydes: formaldehyde and formic acid

Hydrothermal reaction pathways and kinetics of C1 (carbon-one) aldehydes, formaldehyde (HCHO) and formic acid (HCOOH = HOCHO), are studied at 225 degrees C without and with hydrochloric acid (HCl) up to 0.6 M (mol dm(-3)). Reactions unveiled are the following: (i) the self-disproportionation forming methanol and formic acid, a redox reaction between two formaldehydes, (ii) the cross-disproportionation forming methanol and carbonic acid, a redox reaction between formaldehyde and formic acid, and (iii) the acid-catalyzed C-C bond formation producing glycolic acid (HOCH2COOH) as a precursor of the simplest amino acid, glycine. Reaction iii is a hydrothermally induced chemical evolution step from C1 aldehydes, formaldehyde and formic acid. Disproportionations i and ii are found to proceed even without base catalysts unlike the classical Cannizzaro reaction. Acid catalyzes the self-disproportionation (i) and the C-C bond formation (iii), but retards the cross-disproportionation (ii). The rate constants of noncatalyzed and acid/base-catalyzed paths for reactions i, ii, and iii are given additively as 2 x 10(-4) + (2 x 10(-3))[H+], 10(-4) + 10(3)[OH-], and (2 x 10(-3))[H+] M(-1) s(-1), respectively; the concentrations of proton [H+] and hydroxide ion [OH-] are expressed in M. The rate constant of the noncatalytic (neutral) cross-disproportionation is 1 order of magnitude larger than that of the self-disproportionation. The reaction pathways are controlled on the basis of the kinetic analysis to make the glycolic acid and methanol productions dominant by tuning the concentrations of formaldehyde, formic acid, and HCl. The conversion to glycolic acid reaches approximately 90% when formaldehyde, HCl, and formic acid are mixed in the ratio of 1:2:17. The conversion of formaldehyde to methanol reaches approximately 80% when formic acid is added in excess to formaldehyde.     

Molecular fragmentations: Part I. Structures and energies of molecular fragments derived from formic acid

Molecular geometries and heats of formation are calculated, using MINDO/3, for the following mass-spectral fragment pairs derived from formic acid: X(²A')(HCOOH)⁺; (HCOO)⁺ + H^xxx; (HCO)⁺ + OH; HCO + (OH)⁺; (CO)⁺ + H₂O; (CO₂)⁺ + H₂. The activation energy for the reaction (HCOOH)⁺ → (HCOO)⁺ + H^xxx is 75 kJ mol^?1. A correlation is made of the symmetry classes of the electronic states of (HCOOH)⁺, accessible by single electron excitation, and those of the mass-spectral fragments: it is shown that, despite their closely similar appearance potentials, the ions (HCOO)⁺ and (HCO)⁺ arise from different states of (HCOOH)⁺. The structure of (HCOOH)²⁺ is also reported.     

Use of gamma-carboxy-alpha,beta-unsaturated aldehydes as synthetic equivalents of beta,gamma-unsaturated aldehydes in a novel stereoselective approach to diketides

[reactions: see text] A two-step aldol/Pd-catalyzed formate reduction sequence allows for convenient, stereoselective access to products of great potential in synthetic approaches to polyketides. A novel diastereoselective Pd-catalyzed formate reduction of allylic acetates is reported.