Showing papers on "Grignard reaction published in 1969"

Studies on 1, 3-Dithiolium Cations. II. Reactions of 4-Phenyl Derivatives with Nucleophilic Reagents

Abstract: Nucleophilic reagents attacked exclusively to C-2 position of 4-phenyl-1, 3-dithiolium cation derivatives and the corresponding 1, 3-dithioles were obtained in good yields. Thus, 2-amino-, 2-aminothiocarbonylthio-, 2-phenylthio-1, 3-dithioles were yielded. LiAIH4 reduction furnished 1, 3-dithiole and hydride abstraction gave original cation. 1, 3-Dithiolium cation acted as a Bronsted acid and conjugate base carbinol was isolated. Similarly, covalent 2-alkoxy compounds were easily obtained and regenerated cation by the action of acid. Grignard reaction toward cation opened the new routes to 2-substituted 1, 3-dithiolium cations.

Studies in ferrocene derivatives. VII. The synthesis of ferrocenyl ethylenes via an abnormal Grignard reaction

Abstract: RMgBr reacts normally with acylferrocenes to give the corresponding alcohols. RMgI gives good yields of the most highly substituted ferrocenyl ethylene. In solutions of moderate acid strength, α-ferrocenyl carbonium ions lose a proton to form the substituted alkene rather than undergo nucleophilic attack by water to give the corresponding alcohol. Since the alcohols are more basic than the alkenes, it is possible to devise a general synthesis of ferrocenyl ethylenes by the reaction of any Grignard reagent with an acylferrocene.

Asymmetric Reactions. III. Stereoselectivity Difference between Grignard and Alkyllithium Reactions with 2,3-O-Substituted-D-glyceraldehydes

Abstract: Stereoselectivity has been investigated in addition reactions of 2,3-O-isopropylidene-D-glyceraldehyde (I) or 2,3-di-O-benzyl-D-glyceraldehyde (II) with phenylmagnesium bromide or phenyllithium. Stereoselectivity difference between the Grignard and phenyllithium reactions occurred in the case of compound (I): the phenyllithium reaction gives threo and the Grignard reaction erythro products predominantly. On the other hand, no difference in stereoselectivity has been observed between the reactions with 2,3-di-O-benzyl-D-glyceraldehyde (II): both reactions gave threo product predominantly.

Asymmetric Reactions. II. Anomalous Stereoselectivity of the Grignard Reaction with N-Benzyl-2,3-O-isopropylidene-D-glyceraldimine

Abstract: Stereoselectivity of the organomagnesium reaction with N-benzyl-2,3-O-isopropylidene-D-glyceraldimine was examined under various conditions (change of molarity, solvent, and composition ratio of reagents). The selectivity was not effected by the molarity of the reagents but by the solvent. When the substrate was treated with a mixture of various ratio of magnesium bromide and diphenylmagnesium, a remarkable effect of the ratio on the stereoselectivity was observed. Maximum ratio of erythro/threo was obtained at the point of equimolar mixture of magnesium bromide and diphenylmagnesium in ether. The structure of the transition intermediate was discussed.

Some alkylation and Grignard reactions with 1-tetralones and related compounds

Abstract: Convenient routes to 2-monoalkyl- and 2,2-dialkyl-1-tetralones are described. Various 1-(aminoalkyl)-3,4-dihydronaphthalenes and 1-(aminoalkylidene)-1,2,3,4-tetrahydronaphthalenes have been prepared by routes involving a Grignard reaction on the appropriate 1-tetralone. Similar experiments with 4-chromanone and related compounds are reported.

Coupling of allylic halides promoted by iron metal dispersed in dimethyl formamide

Abstract: The coupling reaction of allylic halides to produce non-conjugated dienes was investigated. It was found that iron powder could be utilized, without any special pretreatment, to promote the coupling reaction when a dipolar aprotic solvent was employed as the reaction medium.Effects of variables such as the nature of the halogen atom in the reactive position of the substrate, substituents on the substrate, presence or absence of organic or inorganic halide catalysts, and solvent type were explored briefly.Non-conjugated dienes can be prepared in yields which exceed 90% in the more favorable cases. The present procedure avoids many of the difficulties inherent in such previous methods as the Grignard reaction or the nickel carbonyl-promoted reaction.

Preparation of cholesterol‐25‐3H

Abstract: The synthesis of cholesterol-25-3H (9) described here starts with the readily available 3β-hydroxy-δ5-cholenic acid (1). The acetate of this acid was converted to the next higher homolog by the Arndt-Eistert method. Grignard reaction with methyl iodide gave 25-hydroxycholesterol (6), which was then brominated. Tritium was finally introduced by treating the 25-bromocholesterol (8) with LiAl3H4.

Process for the production of 5-phenyl-1,4-benzodiazepines

Abstract: A PROCESS FOR THE PRODUCTION OF CERTAIN 1,4-BENZODIAZEPINES BY REACTING THE APPROPRIATE GRIGNAED REAGENT WITH THE CORRESPONDING BENZOIDAZEPINE IN SOLUTION IN PYRDINE AND THEEAFTER CONVERTING THE COMPOUND RESULTING FROM THE THE GRIGNARD REACTION TO THE DESIRED COMPOUND, THE GRIGNARD REACTION GENERALLY INTRODUCING A PHENYLGROUP INTO THE 5-POSITION.