Presence Of TMSCl Research Articles

Nitroaromatic bis(2-hydroxyethyl)dithioacetals and oxathioacetals using 2-mercaptoethanol in the presence of chlorosilanes

Thioacetalization of the nitrobenzaldehydes with 2-mercaptoethanol is easily carried out in the presence of TMSCl and dichlorodimethylsilane without heating and using of additional solvent. The reaction direction is defined by the reagents ratio and led to formation of bis(2hydroxyethyl)dithioacetals (yield 76-91%) or 1,3-oxathiolanes (yield 76-91%). Bis(2-hydroxyethyl)dithioacetals are easily transformed in the corresponding 1,3oxathiolanes at long storage without heating or influence of catalysts, and also under electronic and chemical ionization.

ChemInform Abstract: Unexpected Formation of Pyrazolecarbaldehyde Dithioacetal Hydrochlorides

Abstractby acetalization of pyrazole‐4‐carbaldehydes (I) with 2‐sulfanylethanol (II) in the presence of Tms‐Cl

An efficient one-pot protocol for asymmetric bifunctionalization of 5,15-disubstituted porphyrins: direct access to meso activated alkenyl-substituted meso-formylporphyrins

An efficient one-pot protocol for the direct conversion of free base 5,15-disubstituted porphyrins into the corresponding meso activated alkenyl-substituted meso-formylporphyrins has been developed using a sequential SNAr reaction with PyMe2SiCH2Li, conjugate addition to enones or alkenoates in the presence of TMSCl, and oxidation with DDQ.

Synthesis of Two Diastereomers of Iriomoteolide-1a via a Tunable Four-Module Coupling Approach Using Ring-Closing Metathesis as the Key Step

A tunable four-module coupling approach has been established for assembling the 20-membered macrolactone core related to the proposed structure of iriomoteolide-la by using ring-closing metathesis as the key step. Two C1―C6 (2E)-diene acid fragments with (4R,5S)- and (4S,5R)-stereogenic centers, respectively, were synthesized via anti-selective aldol reaction and E-selective conjugate addition of Me 2 CuLi with an alkynoic ester in the presence of TMSCl. The ring-closing metathesis reaction was carried out in the presence of 10 mol% Grubbs second-generation initiator at room temperature to give exclusively the (6E)-cycloalkenes. Our four-module coupling strategy enables efficient synthesis of two diastereomers of the proposed iriomoteolide-la with opposite chirality at C4 and C5.

Unexpected formation of pyrazolecarbaldehyde dithioacetal hydrochlorides

by acetalization of pyrazole-4-carbaldehydes (I) with 2-sulfanylethanol (II) in the presence of Tms-Cl

ChemInform Abstract: Me3SiCl‐Promoted Intramolecular Cyclization of Aromatic Compounds Tethered with N,O‐Acetals Leading to the Facile Preparation of 1,4‐Benzodiazepine Skeletons.

AbstractIntramolecular aminomethylation of aromatic rings with N,O‐acetals tethered via an amine, e.g. (I), (III) or (V), proceeds smoothly in the presence of TmsCl under mild conditions to give a variety of benzodiazepine derivatives.

ChemInform Abstract: One‐Pot Two‐Step Synthesis of N3‐Functionalized 3,4‐Dihydropyrimidinones in the Presence of TMSCl.

AbstractN‐3‐substituted dihydropyrimidinones are regioselectively prepared by using the title procedure concerning the reaction between dihydropyrimidinones, paraformaldehyde (II), chlorotrimethylsilane, alcohols, secondary amine, and sodium salts.

ChemInform Abstract: Acyl Pyruvates as Synthons in the Biginelli Reaction.

AbstractBiginelli type reaction of 2,4‐dioxo‐4‐phenylbutanoate and benzaldehyde with ureas or thioureas is investigated in the presence of TmsCl.

ChemInform Abstract: A Catalytic Role of Cu(II) for Conjugate Addition of Grignard Reagents. A Completely Different Behavior from Organocuprates.

Abstract Different from lithium dialkylcuprates, Cu(II) catalyzed conjugate addition of Grignard reagents to allylic esters of α,β-unsaturated carboxylates has been effected in the presence of TMS-Cl, and the resulting allyl silyl keteneacetals further undergo rearrangement to afford 2-allyl 3-alkyl carboxylic acids in good yields.

ChemInform Abstract: Trimethylsilyl Chloride Assisted Conjugate Addition-Elimination of Organocopper Reagents to 2-Bis(methylthio)nitroethylene: An Efficient and Highly Stereoselective Synthesis of 2-Methylthio-2-alkyl/aryl-1-nitroethylenes and Their Appl

An efficient method for the synthesis of novel 2-methylthio-2-alkyl/aryl-1-nitroethylenes 2 has been developed via conjugate addition-elimination of organocopper reagents to nitroketene dithioacetal 1 in the presence of TMSCl. The product nitroethylenes 2 have been further utilized for the synthesis of substituted 3-nitro-2-alkyl/arylpyrroles 5 by their reaction with aminoacetaldehyde dimethylacetal followed by acid catalyzed cyclization in ethereal HCl. The reaction of 2 with propargyl alcohol has also been investigated.

ChemInform Abstract: Enantioselective Deprotonation Reactions Using a Novel Homochiral Magnesium Amide Base.

A novel homochiral magnesium bisamide base system has been prepared and reacted with a series of prochiral ketones in the presence of TMSCl to give efficient formation of the corresponding enol ethers in enantiomeric ratios of up to 95∶5.

Microwave-Assisted Three-Component Reaction for Rapid Synthesis of Some 5,6-Dihydro-4H-1,3-thiazine Derivatives Under Solvent-Free Conditions

Microwave irradiation was found to efficiently promote the three-component reaction of aromatic aldehyde, thiourea, and vinylbenzene at the presence of TMSCl. The products of 5,6-dihydro-4H-1,3-thiazines were formed in a very short time with good to excellent yields as well as excellent diastereoselectivity. This newly developed protocol provided a much more facile route of preparing functionalized thiazine compounds. [Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental.]

One-Pot Two-Step Synthesis of N3-Functionalized 3,4-Dihydropyrimidinones in the Presence of TMSCl

Novel 3,4-dihydropyrimidinones modified with N3-alkyloxymethyl, aminomethyl, arylsulfonylmethyl, and azidomethyl groups can be regioselectively obtained over their isomeric N1 compounds in good yields by reaction of 3,4-dihydropyrimidinones with paraformaldehyde and alcohol, amine, sodium benzenesulfinate, and sodium azide, respectively, by a one-pot two-step strategy in the presence of chlorotrimethylsilane. The advantages of this method are the simple procedure, the high regioselectivity of the products, no requirement for a base catalyst, and the mild reaction conditions.

ChemInform Abstract: Zinc‐Mediated Allylation and Alkylation of Aminals in the Presence of TMSCl and Diisopropylamine.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

POSS-NEODYMIUM COMPLEX {[(i-C4H9)7(Si7O12)Nd]4NaCl} AS PRECURSOR FOR POLYMERIZATION OF ISOPRENE

The tetrameric neodymium-silsesquioxane cage complex, {[(i-C4H9)7(Si7O12)Nd]4NaCl}, was prepared and used as precursor for the polymerization of isoprene. When activated by AlEt3 in the presence of TMSCl, this POSS-Nd complex (POSS = polyhedral oligomeric silsesquioxane) shows a moderate activity for the polymerization, and the effects of different ratios of Al/Nd, Cl/Nd and time on the polymerization were investigated. Moreover, The POSS-Nd complex may serve as models for the silica-supported rare earth catalyst, and a simplified surface model was also proposed.

Facile and diastereoselective synthesis of β-acetamido ketones and keto esters via direct Mannich-type reaction

A Mannich-type three-component reaction involving aldehydes, acetamide, and enolizable ketones or β-keto esters for the preparation of β-acetamido carbonyl compounds in the presence of TMSCl is described. This newly developed protocol is operationally convenient, widely applicable, and highly diastereoselective.

Zinc-Mediated Allylation and Alkylation of Aminals in the Presence of TMSCl and Diisopropylamine

An alkylation of aminals with organozinc reagents derived from allyl bromide, benzyl bromide, alpha-bromoacetate, and alpha-bromonitrile proceeded efficiently in the presence of TMSCl and diisopropylamine. This reaction system was applied to the synthesis of an antispasmodic: butaverine.

Transformation of gem‐Dicyanoethenes by Samarium: Direct Formation of Indenes or Direct Decyanation with in Situ Disilylation

AbstractIntramolecular cyclization of 1,1‐diaryl‐2,2‐dicyanoethenes promoted by samarium metal in DMF in the presence of TMSCl allowed direct construction of the indene core, whereas 1‐alkyl‐1‐aryl‐2,2‐dicyanoethenes underwent intermolecular coupling cyclization and decyanation under the same conditions. Simultaneously, disilylation occurred at the amino moiety resulting from the reduction of the cyano group. However, only simple reduction of the C=C bonds is observed when a trace amount of water presented.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Efficient catalytic aza-Michael additions of carbamates to enones: revisited dual activation of hard nucleophiles and soft electrophiles by InCl 3/TMSCl catalyst system

The aza-Michael reaction of a variety of chalcones with weaker nucleophilic carbamates catalyzed by InCl 3 in the presence of TMSCl via the entry of dual activation of both hard nucleophiles (carbamates) and soft electrophiles (enones) to provide the corresponding adducts in good yields. The first example of enantioselective aza-Michael reaction of chalcones with carbamates was also investigated in the presence of the present catalyst system.

Conjugate Additions of Me2CuLi to Enantiopure γ-Hydroxy-δ-sulfinyl and Sulfonyl Pentenoates

[reaction: see text] A systematic study of dimethyl cuprate conjugate additions to diastereoisomeric ethyl gamma-hydroxy (or tert-butyldimethylsilyloxy)-delta-p-tolylsulfinyl-2-pentenoates and the analoguous sulfones showed mainly 3,4-anti diastereoselectivity when the reaction occurred in the presence of TMSCl. The pi-facial diastereoselection is mainly governed by the gamma-hydroxy or silyloxy group, whereas the role of the sulfur functionality is to increase the reactivity of the pentenoate system, probably by assisting the transfer of the alkyl group from the cuprate. This was evidenced by the reactions on similar systems that lack the sulfur functions. The appropriate choice of NH4OH or HCl hydrolysis in the workup allowed direct access to the open chain products or the lactones.