Showing papers on "Grignard reaction published in 1983"

Synthesis of the radical scavenger 1,1,3,3-Tetramethylisoindolin-2-yloxyl

Abstract: A versatile free-radical trapping agent, 1,1,3,3-tetramethylisoindolin-2-yloxyl, has been prepared from N-benzylphthalimide by reaction with 'methylmagnesium iodide' in refluxing toluene followed by hydrogenolysis and oxidation. The Grignard reaction gives 2-benzyl-1,1,3,3-tetramethylisoindoline along with a small proportion of an unexpected by-product, 2-benzyl-1-ethyl-1,3,3-trimethyliso-indoline.

The Synthesis of Naturally Occurring C6-C3 and C6-C3-C6 Substances by the Use of Low-Valent Nickel-Mediated Grignard Reactions

Abstract: Etude de la reaction de Grignard entre des alcools, ethers, sulfures allyliques et des bromures de dimethoxy- et trimethoxy-phenyl-magnesium

Alkylation of a Chiral Hydrazone by Means of Asymmetric Addition of Grignard Reagents to the Carbon-Nitrogen Double Bond

Abstract: A chiral hydrazone, (E)-(S)-N'-benzylidene-N, 3-dimethyl-2-hydrazinobutanol (6), was synthesized from (S)-valinol. Compound 6 was reacted with Grignard reagents to give optically pure (2S, 1'S)-N, 3-dimethyl-N'-1'-phenylalkyl-2-hydrazinobutanols (7a and 7b). However, N'-2'-aryl-1'-phenylethyl-N, 3-dimethyl-2-hydrazinobutanols (7c and 7d) were each obtained as a mixture of two diastereomers. Nitrogen-nitrogen bonds of 7a and 7b were cleaved by hydrogenolysis to give (S)-1-phenylalkylamines (8a and 8b), and their absolute configurations and optical purities were confirmed. These reactions were assumed to proceed via the chelated sixmembered ring intermediates.

Asymmetric reaction of chiral azomethines with organometallic reagents.

Abstract: Reaction de [methoxymethyl-1' methyl-2'] propylimine et d'[hydroxymethyl-1' methyl-2'] propylimine du benzaldehyde avec le bromure d'ethyl-magnesium suivie d'une reaction de N-methylation (iodomethane)

Synthesis of dl-α-Tocopherol and dl-α-Tocotrienol

Abstract: α-Tocopherol (1) and α-tocotrienol (2) were synthesized in racemic form by a method in which their side chains were constructed by the coupling reaction of a key intermediate, 6-methoxymethoxy-2, 5, 7, 8-tetramethyl-2-(5-mercaptothiazolinyl-4-methyl-3-penten-1-yl) chroman (7), with geranyl bromide. Desulfurization of the reaction product and then hydrolysis afforded α-tocotrienol, which, upon reduction, gave the desired α-tocopherol in good yield. This method, using a mercaptothiazolinyl derivative, is more convenient than previous approaches which use the Wittig or Grignard reaction for the synthesis of the side chain.

Synthesis and analysis of 1-octen-3-ol, the main flavour component of mushrooms.

Abstract: The most abundant volatile occurring in mushrooms and responsible for the mushroom odour is 1-octen-3-ol. To meet the demand for a flavour compound yielding a mushroom odour a study was carried out on the possibility of obtaining 1-octen-3-ol synthetically. On the basis of literature data and experiments performed, the synthesis of this compound was carried out by two methods, i.e. by Grignard reaction between acrolein and amyl iodide and by selective reduction of 1-octen-3-on. The purity of the 1-octen-3-ol obtained was determined by GLC chromatography and by spectroscopic methods. The compound obtained by Grignard reaction had its IR, 13C NMR spectra and GLC chromatogram identical with those of the standard. The yield of 1-octen-3-ol by Grignard reaction was 65%, while the reduction of the ketone to the alcohol gave a yield of 90%.

Asymmetric α-Substituted Phenethylamines. II. The Enantioselective Synthesis of 1-Aryl-2-phenylethylamines from L- and D-Amino Acids by Means of 1, 3-Asymmetric Induction

Abstract: Optically pure (1S, 1'S)-1-aryl-N-(1'-alkyl-2'-hydroxyethyl)-2-phenylethylamines (13-21) were synthesized from L-alanine, L-leucine, and L-isoleucine via (S)-2-aminoalkanols (1-3) and (E)-(S)-N-(1-alkyl-2-hydroxyethyl) arylmethylideneamines (4-12). On the other hand, the amines with (1R, 1'R) configuration (33-38) were synthesized from D-amino acids, i.e., D-alanine and D-leucine. The absolute configurations of these amines were confirmed by the aromatic quadrant-sector rule. The asymmetric reactions of chiral azomethines (7-12 and 30-32) with benzylmagnesium chloride were found to be extremely highly stereoselective. However, the reactions of the azomethines (4-6 and 27-29) derived from L- and D-alanine with the Grignard reagent afforded poor stereoselectivity.

Studies of Aromatic Sesquiterpenes. IV. The Synthesis of γ-Calacorene, Calamenene, and 4-Methoxyisocadaiene

Abstract: The Grignard reaction of 3,4-dihydro-4,7-dimethyl-1(2H)-naphthalenone with isopropylmagnesium bromide gave a 3 : 1 mixture of normal reaction product and α-isopropylidene ketone, from which, the title sesquiterpenes and 1,2-bis(3-isopropyl-4-methoxy-6-methyl-1-naphthyl)ethane were synthesized.

Convenient synthetic route to 6,8-dioxabicyclo[3.2.1]octanes, the aggregation pheromone components of bark beetles

Abstract: Convenient syntheses of (±)-frontalin (I) and (±)-brevicomins (IIa) and (IIb) were achieved from pent-4-en-1-ol (2) and pent-4-yn-1-ol (3). In a few simple and unambiguous steps, the alkenol (2) and the alkynol (3) were transformed into the acetal bromide (7) and the alkenyl bromides (14) and (17), respectively. Acylation of the Grignard reagents of these bromides provided the corresponding methyl ketones (8), (15), and (18), the key intermediates for the synthesis of the title bicyclic acetals. The ketone (8) was converted into the olefin (9) which, on epoxidation followed by acid hydrolysis, yielded (±)-frontalin, whereas epoxidation of the alkenones (15) and (18) and subsequent cyclisation afforded exo-and endo-brevicomin, stereoselectively.

Production of silicon-containing organic high-molecular compound

Abstract: PURPOSE: To facilitate the formation of the linear high-molecular compound suitable for use in paints, etc., by polymerizing a specified vinylsilane derivative under a condition under which the vinylsilyl group can remain intact but the ethylenic double bond in the organic group can be preferentially polymerized. CONSTITUTION: A vinylsilane derivative of the formula (wherein V is an organic group having a polymerizable ethylenic double bond, R 1 and R 2 are each a 1W 4C alkyl or phenyl, and n is 0W3) is prepared by using vinylchlorosilane, etc., as starting materials and subjecting them to a Grignard reaction, etc. The purpose high-molecular compound of a linear structure is obtained by polymerizing the vinylsilane derivative by a polymerization process by which the vinylsilyl group can remain intact but the ethylenic double bond can be preferentially polymerized, such as radical polymerization process or anionic polymerization process. A three-dimensional polymer compound can be readily obtained by crosslinking the vinylsilyl groups of the polymer. COPYRIGHT: (C)1985,JPO&Japio

Indolenine Oxides, VIII. Reaction of 5,7-di-tert-butyl-3,3-dimethyl-3H-indole 1-Oxide with Grignard Reagents. – A New Stable Aminyl Oxide (Nitroxide)

Abstract: The title compound 1, unsubstituted at C-2, is efficiently converted into its 2-substituted derivatives 4a,b by Grignard addition and lead dioxide oxidation. 4a, when subjected to the same sequence, gives high yields of the aminyl oxide 5a which is also formed in small amounts in the conversion of 1 together with two other minor compounds. The course of the reaction is influenced by the presence of a bulky tert-butyl group at C-7 in 1 and by the solvent used for the Grignard reaction.

Optically active diallylbis(2-phenylbutyl)tin. Synthesis and application to asymmetric synthesis of homoallyl alcohols.

Abstract: Optically active diallylbis(2-phenylbutyl)tin (1) was successfully obtained by the Grignard method. Enantioselective reaction of 1 with various aldehydes afforded homoallyl alcohols in 20–80% optical yields, which are not affected by solvent effect, but are highly dependent on aldehydes.

Synthetic studies on a picrotoxane sesquiterpene, coriamyrtin. I. The Grignard reaction of 5-(2-methyl-1,3-dioxo-2-cyclopentyl)methyl-2,5H-furanone with isopropenylmagnesium bromide and stereochemistries of the products.

Abstract: 1, 6-Addition of 2-methyl-1, 3-cyclopentanedione (8) to protoanemonin (7) gave 5-(2-methyl-1, 3-dioxo-2-cyclopentyl) methyl-2, 5H-furanone (6). The Grignard reaction of 6 with isopropenylmagnesium bromide-cuprous iodide provided two kinds of lactones, (10) and (11), in excellent yield through 1, 4-addition of the Grignard reagent to 6 and the subsequent internal aldol cyclization. These lactones, however, possessed the undesired stereostructures for the present synthesis and conversion of the lactone (10) into the desired lactone (4) was performed by retroaldol cleavage and subsequent internal aldol recyclization as shown in Chart 6.

Reaction of 14CO2 with grignard reagents to form either carboxylic acids or ketones. A novel convenient route to [2-14C] glycerol and [1-14C] Glycolic acid

Abstract: The reaction of CO2 with GRIGNARD reagents carrying an ether grouping in a sterically suitable position can be directed to afford predominantly either the carboxylic acid or the symmetrical ketone. Thus, the magnesiumorganic compounds prepared from chloromethyl-methyl ether, benzyl-chloromethyl ether and 2-methoxy-bromobenzene, upon treatment with CO2 under appropriate conditions give the corresponding ketones in excellent yield. An attempt is made to rationalize this finding from a mechanistic viewpoint. The easily accessible 1,3-bis(benzyloxy)-acetone represents a convenient intermediate for an efficient and simple synthesis of glycerol.

1,3-dihydroxybenzene-2-13C: Its preparation and reaction with chlorine and bromine in aqueous solution

Abstract: 1,3-cyclohexanedione-2-13C was prepared by intramolecular Claisen condensation of methyl 5-oxohexanote-6-13C with sodium methoxide. Formation of the ketoester starting material involved treatment of a mixed dicarboxylic anhydride with an isotopicallylabelled Grignard reagent, methyl-13C magnesium iodide. Dehydrogenation of carbon-13 labelled cyclohexanedione over a palladium/carbon catalyst produced 1,3-dihydroxybenzene-2-13C. Chlorination and bromination of dihydroxybenzene in aqueous solution yielded isotopically-labelled chloroform and bromoform, each having enriched carbon-13 contents equivalent to that of the organic substrate.

Process for the photopolymerization of unsaturated compounds

Abstract: Compounds of the formula I, II, III, IV or V ##STR1## in which Ar, X, Y, Y', R 1 to R 5 and R 1' to R 5' are as defined in claim 1, can be used as photoinitiators for the photopolymerization of unsaturated compounds. They can be prepared by a Diels-Alder reaction and/or a Grignard reaction.

The preparation and photolysis of (E)-1-Aryl-3-methyl-3-phenylbut-1-enes

Abstract: Reaction of 2-methyl-2-phenylpropylmagnesium chloride with benzaldehyde in tetrahydrofuran gave 2,7-dimethyl-2,4,5,7-tetraphenyloctane-4,5-diol as a 1 : 2 mixture of clear transparent crystalline plates (meso) and needles (±), 3-methyl-1,3-diphenylbutan-1-one, benzyl alcohol, 2-methyl-2-phenylpropaneand a low yield of 3-methyl-1,3-diphenylbutan-1-ol. The distinction between the meso and the (+)- diols was unequivocal because the unique space group of the former requires thedimeric molecules to lie about a crystallographic centre of symmetry. The mechanism involved in the formation of the products of the Grignard reaction is examined. By careful choice of reaction conditions a series of I-aryl-3-methyl-3-phenylbutan-1-ols were prepared. Dehydration of the 1-aryl-3-methyl-3-phenylbutan-1-ols with p-toluene sulfonic acid and a short reaction time gives(E)-1-aryl-3-methyl-3-phenylbut-1-enes but longer reaction times afford 3-aryl-1,1-dimethylindanes.Photolysis of the (E)-1-aryl-3-methyl-3-phenylbut-1-enes affords (Z)-1-aryl-3-methyl-3-phenylbut-1-enes and trans-1-aryl-3,3-dimethyl-2-phenylcyclopropanes. Extended photolysis gives 4-aryl-2-methyl-3-phenylbut-1-enes via trans-1-aryl-3,3-dimethyl-2-phenylcyclopropane by rupture of the cyclopropyl bond adjacent to the aryl substituent.

Synthesis of diethyl 4-(benzothiazol-[2-14C]-2-yl) benzylphosphonate ([14C]KB-944)

Abstract: Diethyl 4-(benzothiazol-[2-14C]-2-yl)benzylphosphonate ([14C]KB-944), a new calcium antagonist, was prepared from labelled carbon dioxide. The synthetic intermediate, [14C]p-toluic acid, obtained by the Grignard reaction was condensed with 2-aminothiophenol, brominated with N-bromosuccinimide, and followed by the Arbuzov reaction. [14C]KB-944, having the specific activity 52.7 mCi/mmol, was obtained in 36% overall yield from [14C] barium carbonate and its radiochemical purity was 99.3% in reverse isotope dilution analysis.

Process for preparation of arylterpenoid insect maturation inhibitors

Abstract: There is provided an improved process for producing biologically active arylterpenoid compounds useful to inhibit eclosion of pupae, e.g., fly pupae or mosquito pupae. The process is characterized by reacting a terpenoid material having a terminal unsaturated linkage, e.g., dihydromyrcene (3,7-dimethylocta-1,6-diene) with a lower alkyl Grignard reagent, e.g., n-propyl magnesium chloride to form a Grignard exchange product. The exchange product is then benzylated. Either a benzyl halide, e.g., p-isopropylbenzyl chloride, or a benzaldehyde, e.g., p-isopropylbenzaldehyde may be used. These compounds are specifically described in U.S. Pat. No. 4,002,769. They contain also a lower alkoxy group, e.g., methoxy. This can be introduced prior to the formation of the Grignard exchange product or at a later stage in the operation. Use of the exchange-type Grignard reaction enables elimination of several steps when producing the arylterpenoids from pinene as the terpene source, and consequent costs.

4(5)-Acetyl-2-methylimidazole process

Abstract: Process for making 4(5)-acetyl-2-methylimidazole, a valuable intermediate, from 2-methylimidazole-4(5)-carboxaldehyde, the 1-position of which is protected by a benzyl group which may be unsubstituted or substituted. The process comprises a Grignard reaction followed by deblocking and oxidation, or by oxidation then deblocking. The oxidation is effected in a reaction-inert solvent with manganese dioxide.

Synthesis of trideuterated stanozolol labelled selectively at the 17-methyl group

Abstract: A synthetic procedure for stanozolol-d3 is described. Deuterium labelling was achieved by the Grignard reaction of androstan-3β - ol - 17 - one with deuterium labelled methyl magnesium iodide (CD3 Mg I). The synthesis was achieved in five steps from Δ5-androstan-3-β-ol-17-one in an overall yield of 15%. The procedure resulted in a product which was selectively deuterated and chemically pure.

A reinvestigation of the synthesis of 4-methyl-3-heptanol

Abstract: A previously reported laboratory may have reported gas chromatographic separation of the 4-methyl-3-heptanol diastereomiers in error. The side reactions in the Grignard reaction account for the obs...

Preparation of dihydrotagetone from methacrolein acetal as raw material

Abstract: PURPOSE:To obtain dihydrotagetone which is a component in a floral perfume in short steps industrially and advantageously without using the oxidative reaction or Grignard reaction, by obtaining a gamma-ketoaldehyde from an easily available methacrolein acetal as a raw material, and subjecting the resultant gamma-ketoaldehyde to the Wittig reaction. CONSTITUTION:Methacrolein acetal of formula I obtained from methacrolein as a raw material is subjected to the radical addition reaction with 3-methylbutanal of formula II to give a gamma-ketoaldehyde acetal of formula III, which is then hydrolyzed with sulfuric acid, etc. to afford a gamma-ketoaldehyde of formula IV. The resultant gamma-ketoaldehyde of formula IV is then subjected to the Wittig reaction with methylenetriphenylphosphorane of fomula V to prepare dihydrotagetone(2,6-dimethyl-7-octen-4-one) of formula VI.