Council of Scientific and Industrial Research

Arun Kumar Sinha

Bhupendra Prasad Joshi

Ruchi Dogra

Rakesh Kumar

Anuj A Sharma

Abhishek Sharma

Naina Sharma

Vinod Kumar

Ruchi Acharya

Anand Swaroop

A microwave-induced process for the preparation of 2-aryl and 2,2-diaryl aldehydes and analogs wherein halohydrin formation and subsequent rearrangement to 2-aryl aldehydes from corresponding aryl alkanols occurs without formation of an intermediate epoxide or use of transition metal catalysts or lewis acids/bases.

Microwave induced single step green synthesis of some novel 2-aryl aldehydes and their analogues

The present invention provides a process for the preparation of some novel 2-aryl and 2,2-diaryl aldehydes and analogues which are privileged intermediates for commercially important nonsteroidal anti-inflammatory drugs including naproxen, flurbiprofen and potent anticancer drug candidates, including phenstatin through a unique single step synthetic methodology utilizing easily available substrates in the form of aryl alkenes as well as environmentally benign aqueous reaction conditions in the form of solvents such as mixtures of water and DMSO or Dioxane and reagents N-bromosuccinimide, N-iodosuccinimide, N-cholorosuccinimide and phase transfer catalyst such as cetyltrimethyl ammonium bromide, N-hexyl ammonium chloride for a reaction time varying from 1 min-30 min, depending upon microwave or conventional heating, without using expensive transition metal catalysts or lewis acids/bases with yield varying from 35-55%, depending upon the solvent and substrate used. The developed method provides a clean and convenient alternative to access a diverse range of medicinally important 2-aryl and 2,2-diaryl aldehyde based scaffolds in lieu of the conventional multistep protocols employing expensive and hazardous transition metal catalysts and lewis acids/bases.

The present invention provides a method for the preparation of some novel multiconjugated 2- or 4-hydroxy substituted stilbenes. The method provides one pot multicomponent approach wherein 3-4 step reaction sequences viz. condensation, decarboxylation and Heck coupling occur simultaneously which results in an enhanced yield of desired products and reduced reaction times.

One pot multicomponent synthesis of some novel hydroxy stilbene derivatives with alpha, beta-carbonyl conjugation under microwave irradiation

The invention entitled 'A Microwave Induced One Pot Process for The Preparation of Arylethenes' provides a method for the preparation of commercially important 2- or 4-hydroxy substituted arylethenes like styrenes or stilbenes in one pot utilizing cheaper substrates in the form of 2- or 4-hydroxy substituted cinnamic acids and their derivatives as well as reagents in the form of base such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, ammonium acetate, imidazole, methylimidazole and the combination thereof, with or without solvent such as dimethylformamide, dimethylsulfoxide, ethylene glycol, diethylene glycol, acetonitrile, acetone, methyl imidazoles, ionic liquid, water and the like. The reaction time vary from 1 min-12 hrs and yield of the products from 49-76% depending upon the base, acid, substrate source of heating monomode or multimode microwave or conventional. It is important to mention that the presence of 2- or 4-hydroxy substitution at phenyl ring of cinnamic acids and their derivatives is essential requirements towards formation of corresponding arylethenes in one step.

Microwave induced one pot process for the preparation of arylethenes

The invention provides a green process for direct oxidation of a large number of substituted or unsubstituted cinnamaldehydes or cinnamyl alcohols into the corresponding alkyl or aryl cinnamates in one step. The process of the present invention is a convenient and efficient green process for the preparation of various aryl or alkyl cinnamates under conventional, microwave and ultrasound directly from cinnamaldehydes or cinnamyl alcohols in the presence of an oxidizing agent, catalyst and an alcohol, with or without an organic solvent. These esters are immensely important compounds in flavor, perfumery and pharmaceutical industries. There are several prior arts available for the preparation of cinnamic esters, but all of them suffer from deficiencies such as use of expensive reagents and catalysts, harsh reaction conditions, use of toxic chemicals and others. In contrast, the present methodology is extremely simple and involves reaction of the substrate with an oxidizing agent mixed with a homogeneous or heterogeneous catalyst and an alcohol with or without organic solvent by stirring at room temperature or refluxing or under microwave or ultrasound irradiation to get the requisite products.

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The present invention relates to 'a microwave induced process for the preparation of 4-vinylphenols or its derivatives' in which commercially important FEMA GRAS approved perfumery and flavouring vinylphenols (i.e. hydroxystyrenes) namely 4-vinylguaiacol (FEMA GRAS No. 2675) and 4-vinylphenol (FEMA GRAS No. 3739) as well as other useful vinylphenols such as 2,6-dimethoxy-4-vinylphenol, 2-hydroxy-4-vinylphenol, 3-hydroxy-4-vinylphenol etc. by condensation of malonic acid and 4-hydroxyphenylaldehydes or its derivatives.

Microwave induced process for the preparation of substituted 4-vinylphenols

The present invention relates to neolignan (NEOLASA-I) 3-ethyl-2-methyl-3-(2&#x2033;,4&#x2033;,5&#x2033;-trimethoxy-phenyl-1-(2',4&#x2032;,5&#x2032;-trimethoxy)phenyl-1-propene and a process for the preparation of high purity, higher yield neolignan, &#x3b1;-asarone, 2,4,5-trimethoxy-phenyl propionone from &#x3b2;-asarone or &#x3b2;-asarone richoil containing &#x3b1; and &#x3b3;-asarone by hydrogenating and dimerizing by treatment with DDQ in presence of an organic acid.

DDQ mediated one step dimerization of &#x3b2;-asarone or &#x3b2;-asarone rich Acorus calamus oil in the formation of novel neolignan

A natural inexpensive acyclic monoterpene ketone (dihydrotagetone) of formula (4), isolated from the oil of sp., was smoothly oxidized with meta-periodate/potassium permanganate into 2,6-dimethyl-4-oxo-heptanoic acid of formula (3), the reduction of 3 with metal hydride such as sodium borohydride or lithium aluminium hydride provided 4-hydroxyacid of formula (2) which on without isolation undergone lactonisation in acidic medium furnished two chiral centered 5-isobutyl-3-methyl-4,5-dihydro-2(3H)-furanone of formula (1) as an analogue of whisky lactone 5-butyl-4-methyl-4,5-dihydro-2(3H)-furanone of formula (1a) responsible for high quality of alcoholic beverage (whisky, wine, brandy and scotch), in addition, coconut flavoured 5-butyl-4-methyl-4,5-dihydro-2(3H)-furanone of formula (1) is also as an analogue of coconut aldehyde (&ggr;-nonalactone, F.E.M.A. No. 2751) of formula (1b) which is responsible for flavouring a wide range of food stuffs including baked goods and confectionery.

Heptanonic acid and furanone compounds and compositions

The present invention relates to a process for the preparation of high purity and yield &agr;-asarone, trans 2,4,5-trimethoxy cinnamaldehyde, 2,4,5-trimethoxy-phenyl propionone, from &bgr;-asarone or &bgr;-asarone rich oil containing &agr; and &ggr;-asarone by hydrogenating, followed by treatment with DDQ with or without solid support of silica gel or alumina in dry organic solvent and &agr;-asarone can also be obtained by treating the hydrogenated product of &bgr;-asarone or &bgr;-asarone rich with DDQ in an aqueous organic solvent to obtain an intermediate 2,4,5-trimethoxy phenyl propionone, which in turn is reduced with sodiumborohydride to obtain the corresponding 2,4,5-trimethoxy-phenyl propanol and followed by final treatment with a dehydrating agent.

Process for the preparation of pharmacologically active &agr;-asarone from toxic &bgr;-asarone rich acorus calamus oil

A natural inexpensive acyclic monoterpene ketone (dihydrotagetone) of formula (4), isolated from the oil of Tagetes sp., was smoothly oxidized with meta-periodate/potassium permanganate into 2,6-dimethyl-4-oxo-heptanoic acid of formula (3), the reduction of 3 with metal hydride such as sodium borohydride or lithium aluminium hydride provided 4-hydroxyacid of formula (2) which on without isolation undergone lactonization in acidic medium furnished two chiral centered 5-isobutyl-3-methyl-4,5-dihydro-2(3H)-furanone of formula (1) as an analogue of whisky lactone 5-butyl-4-methyl-4,5-dihydro-2(3H)-furanone of formula (1a) responsible for high quality of alcoholic beverage (whisky, wine, brandy and scotch), in addition, coconut flavored 5-butyl-4-methyl-4,5-dihydro-2(3H)-furanone of formula (1) is also as an analogue of coconut aldehyde (&ggr;-nonalactone, F.E.M.A. No. 2751) of formula (1b) which is responsible for flavoring a wide range of food stuffs including baked goods and confectionery.

Method for producing chiral dihydrotagetone, and its conversion to chiral 5-isobutyl-3-methyl-4,5-dihydro-2(3H)-furanone

The present invention relates to the preparation of substituted trans-cinnamaldehyde, a natural yellow dye from Phenylpropane derivatives having R &mdash;R &mdash;R &mdash;R &mdash;R substitution, wherein R to R equal or different, being hydrogen or hydroxy or acyl or halogen or alkyl or heterocyclic or aryl or dioxymethylene or alkoxy groups, etc., by oxidizing the said phenylpropane derivatives using a oxidising agent such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or p-chloranil or pyridinium chlorochromate (PCC) or tBuOOH or CrO with a catalytic amount of inorganic/organic acid or alumina, celite, and silica gel as a solid support for microwave irradiation and thus substituted trans-cinnamaldehydes, a natural yellow dye, are obtained in high yield ranging from 68-82%.

Process for the preparation of substituted trans-cinnamaldehyde, a natural yellow dye, from phenylpropane derivatives

Microwave assisted rapid and economical process for the preparation of substituted phenylaldehydes from trans and cis-phenylpropenes: a commercial utilisation of toxic cis-isomer

The invention relates to a process for the preparation of 1-Propyl-2, 4, 5-trimethoxybenzene useful as a aroma molecule and as a starting material and intermediate for preparation of various drugs. The process comprises providing crude calamus oil or &bgr;-asarone in a solvent; hydrogenating the solution in the presence of a catalyst; filtering the catalyst and removing the solvent under reduced pressure; subjecting the reduced calamus oil to column of silica gel chromatography using an eluent to obtain the desired product in liquid form with 85-97% purity.

Process for the preparation of 1-Propyl-2, 4, 5-trimethoxybenzene from toxic &bgr;-asarone of acorus calamus or from crude calamus oil containing &bgr;-asarone

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Himachal Pradesh, India

Arun Kumar Sinha