Some perfluoroalkyl grignard reagents and their derivatives

Some perfluoroalkyl Grignard reagents have been prepared in high yields through halogen-metal exchange reactions between perfluoroalkyl iodides (R_fI) and EtMgBr. Derivatization with Me₃SiCl gave satisfactory yields of the corresponding silylated products in THF. However, ether was a very poor solvent for reaction of R_fMgBr with these chlorosilanes. The exchange reaction between R_fI and EtMgBr was nearly quantitative in ether as evidenced by high yields of the 1-hydroperfluoroalkanes upon hydrolysis, but the major production from the attempted silylation in ether was a trans- vinyl bromide [1], i. e.

Spectral data are presented for several new compounds.     

Reaction of polyepichlorohydrin with magnesium and grignard reagents

The reaction of polyepichlorohydrin with magnesium in tetrahydrofuran at reflux temperature was studied in the hope of obtaining a polymeric Grignard reagent. The polymeric Grignard reagent could not be obtained, but dechlorination occurred. It was confirmed that the Grignard reagent of polyepichlorohydrin was formed as an intermediate during the dechlorination. The reactions of polyepichlorohydrin with Grignard reagents were carried out in tetrahydrofuran at reflux temperature. Benzylmagnesium chloride and allylmagnesium chloride were used as Grignard reagents. It was found that the chlorine atom in polyepichlorohydrin can be replaced by benzyl and allyl groups. The extent of the substitution increased with increasing concentration of Grignard reagent. Dechlorination and scission of the ether linkage occurred simultaneously as side reactions.     

Reaction of 2-heterosubstituted benzothiazoles with allylic grignard reagents

The title benzothiasoles $\text{1}$ react with allylic Grignard reagents affording 2-allylbenzothiazoles $\text{5}$, 2,2-diallyl- benzothiazolines $\text{6}$ and N-triallylmethyl-o-aminobenzenethiols as disulphides $\text{7}$ depending upon the experimental conditions. The reaction is considerably influenced by the solvent used and the nature of the allylic Grignard. A possible mechanism for the formation of compounds $\text{5}$, $\text{6}$ and $\text{7}$ is reported.     

Benzopyranopyridine derivatives 3. Reaction of 1-azaxanthone with grignard reagents

Three different classes of compounds were isolated in the reaction of Grignard reagents with 5-H[1]benzopyrano[2,3-b]pyridin-5-one, commonly called 1-azaxanthone. The formation of (a) 4-substituted 1,4-dihydro-1-azaxanthones (II), (b) 5-substituted-5-hydroxy-1-azaxanthenes (III) or (c) 4,5-disubstituted-1-azaxanthenes (IV) is dependent on the solvent used in the preparation of the Griganrd reagent (i.e. ether or tetrahydrofuran), the steric properties of the reagent and on the temperature. The isolated compounds were characterized by chemical derivatives and/or spectroscopic analyses.     

Reaction of poly(vinyl chloride) with magnesium and grignard reagents

Reaction of poly(vinyl chloride) with magnesium under various conditions was attempted, but poly(vinyl chloride) did not react with magnesium. The reactions of poly(vinyl chloride) with benzylmagnesium chloride and allylmagnesium chloride as Grignard reagents were carried out in tetrahydrofuran at reflux temperature. It was found that the chlorine atoms in the poly(vinyl chloride) were replaced by benzyl and allyl groups by the coupling reaction, and a small amount of Grignard reagent of poly(vinyl chloride) was formed by the magnesium–halogen exchange reaction. The extent of the substitution increased with increasing reaction time and concentration of the Grignard reagent.     

Oxonitriles: a grignard addition-acylation route to enamides

[reaction: see text] Sequential addition of three different Grignard reagents and pivaloyl chloride to 3-oxo-1-cyclohexene-1-carbonitrile installs four new bonds to generate a diverse array of cyclic enamides. Remarkably, formation of the C-magnesiated nitrile intermediate is followed by preferential acylation by pivaloyl chloride rather than consumption by an in situ Grignard reagent. Rapid N-acylation of the C-magnesiated nitrile generates an acyl ketenimine that reacts readily with Grignard reagents or a trialkylzincate, effectively assembling highly substituted, cyclic enamides.     

A regioselective route to 5-substituted pyrazole- and pyrazoline-3-phosphonic acids and esters

The regioselective synthesis of 5-substituted-3-dimethoxyphosphono-pyrazoles and -2-pyrazolines has been accomplished through the 1,3-dipolar cycloaddition of a suitable nitrile imine to monosubstituted alkynes and alkenes. Examples of hydrolysis of the heterocyclic phosphonic esters to the corresponding acids are described.     

Reaction of 2-methoxy-1,3-dioxane with grignard reagents: reagent-substrate complexation and stereoelectronic control.

The stereoelectronically controlled reaction of 2-methoxy-1,3-dioxane ($\text{1}$) with Grignard reagents does not follow the course suggested by the behavior of anancomeric models for the conformational isomers of $\text{1}$. Treatment of $\text{1}$ with RMgX leads to the predominant formation of acid labile 3-(1′-methoxyalkoxy)-1-propanols, derived from endocyclic cleavage of the ring CO bond, and only minor amounts of the expected 2-R-1,3-dioxanes.     

Some new aspects of conjugate addition of grignard and alkyllithium reagents to vinylsilanes

A structure and reactivity relationship has been determined on the reaction of isopropyl and n-butyl Grignard reagents and n-butyllithium with vinyl-(alkoxy)silanes and (amino)silanes. The addition to the vinyl group has been analyzed in terms of the nucleophile HOMO-vinyl group LUMO interaction.     

Reaction of mixed carboxylic anhydrides with grignard reagents : Application to the preparation of keto esters; scope and limitations

The low-temperature Grignard reaction of mixed carboxylic anhydrides derived from acid chlorides and o-anisic acid to the general synthesis of keto esters is demonstrated for compounds 1–6, although, some limitations on substrate and Grignard reagent species are also encountered; attempts in the oxa series 2 are unsuccessful, and reaction with ω-phenylpropyl Grignard species for 1 and 4 shows a drastic decrease in yields of the keto esters for m-methoxy analogues. Anomalous behaviour may be associated with an alternative type of specific metal-coordination complex which includes the ether oxygen atom properly situated in the substrate or the reagent     

Reaction of phosphorus trichloride with carboxylic acids

The reaction of phosphorus trichloride with a number of monobasic carboxylic acids has been studied and the optimum ratio of reactants for the yield of acid chlorides has been established. Based on analysis and the data from³¹P NMR spectroscopy of the phosphorus-containing products from this reaction it is shown that at 402-50°C a mixture of P-H acids having a predominant content of pyrophosphorous acid is formed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 428–432, February, 1990.     

Reaction of phosphorus monothio acids with oxetanes

Conclusions The reaction of dialkylthiophosphoric and cyclic six and seven-membered thiophosphoric acids with oxetanes gives the S-3-hydroxyalkyl esters of these acids. During synthesis the S-3-hydroxyalkyl esters of the five-membered cyclic thioacids undergo rearrangement to the 3-mercaptoalkyl derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1128–1130, May, 1981.     

Double addition of grignard reagents to N-glycosyl nitrones: a new tool for the construction of enantiopure azaheterocycles

[Reaction: see text] C-Phenyl-N-erythrosylnitrone 3 behaves as a C1,C1' bis-electrophile, undergoing a double addition of Grignard reagents in a domino fashion to afford acyclic hydroxylamines 4. The reaction proceeds at 0 degrees C with variable degrees of diastereoselectivity, from moderate to good, mainly depending on the organomagnesium reagent used. The usefulness of compounds 4 has been exemplified with the synthesis of pyrroloazepine 12 through a ring closing metathesis key step.