1,720,993 research outputs found
L’impatto della multicanalità e dei customer generated media sulle politiche di comunicazione delle imprese: un’indagine esplorativa
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THE PREPARATION OF 4-CHLORO-2,6-DIALKYL-, 4-BROMO-2,6-DIALKYL-, (E/Z)-4-CHLORO-2,6-DIALKYL-3-METHYL-AND (E/Z)-4-BROMO-2,6-DIALKYL-3-METHYL-TETRAHYDROPYRANS BY CONDENSATION OF ALDEHYDES WITH DI-HALIDES AND TRI-HALIDES OF ALLYLTIN .9.
No full textThe reaction recently discovered leading to tetrahydropyrans (THP): has been more extensively investigated by using various allyltin systems, alternate incremental additions of two aldehydes, and scrambling organotin reagents. Unsymmetric halotetrahydropyrans containing various R groups can be readily prepared in this way.
The thermal breakdown of the 12-dichloro adducts, namely (E/Z)1-alkyl-1-butyldichlorostannoxy, 1-alkyl-3-pentyl ethers and the (threo/erythro)-1-alkyl-1-butyldichlorostannoxy, 1-alkyl-2-methyl-3-butenyl ethers, is a stereospecific reaction which affords (E/Z)-halotetrahydropyrans, where the isomerism is at the CHClCH(CH3) bon
Users’ search mechanisms and risks of inappropriateness in healthcare innovations : the role of literacy and trust in professional contexts
Full text linkIn the context of professional service organizations, user engagement with knowledge search might generate significant risks of inappropriateness to innovation processes. Previous research suggests that professionals would then keep users at arms' length, controlling the design and implementation of innovations internally. This study overcomes this view investigating how professional service organizations can enable users' knowledge search while controlling for the risks of inappropriateness. Combining a qualitative research on 5 innovation processes in healthcare organizations with quantitative research on 110 service users, our findings highlight that professional providers, such as senior clinicians, shaped their tactics according to the ‘threats’ of laggards, i.e. users searching knowledge outside of professional logics of appropriateness; more than to the opportunities of lead-user communities. Professional providers sought to “activate” users' engagement with knowledge search by investing on their literacy, i.e. showing the basics of the logic of appropriateness informing their decision; and on trust relationships, i.e. becoming transparent on the criteria of knowledge selection during the innovation processes
ALLYLSTANNATION .8. A FACILE METHOD FOR THE SYNTHESIS OF 1,5-DIEN-4-OLS BY REACTION OF BU2CLSNCH2CH=CH2 WITH ALPHA,BETA-UNSATURATED CARBONYL-COMPOUNDS
No full textAllylstannation III. Synthesis of homoallylic alcohols and 4-chloro-2,6-dialkyl-3-methyltetrahydropyrans by reactions between (E/Z)-2-butenyldichloro-n-butyltin and aldehydes
No full textABSTRACT: 2-Butenyldichloro-n-butyltin (in various cis/trans isomer ratios) reacts readily with neat RCHO (R = CH3, C2H5, (CH3)2CH, and C6H5) at 25°C to give (a) linear alcohols, RCH(OH)CH2CHCHCH3 in the E and Z forms, (b) branched alcohols, RCH(OH)CH(CH3)CHCH2 in the threo and erythro forms, and (c) 2,3,4,6-tetra-substituted tetrahydropyrans (A) as a mixture of cis/trans isomers arising from the CH(CH3)CHCl bond. The maximum yields of these tetrahydropyrans were obtained{A figure is presented} by the use of 3-3.5 molar ratios RCHO/tin compound in the absence of solvent, whereas work-up after reactions in CH2Cl2 gave linear, alcohols as the main products. The formation of linear alcohols appears to be stereospecific, as the ratio of E/Z isomers obtained is the same as that in the organotin compound. Tetrahydropyrans are formed preferentially as the trans isomer
ALLYLSTANNATION .7. PREPARATION OF CARBOXYLIC-ACID 1-ALKENE-4-YL AND 1-ALKYNE-4-YL ESTERS BY TRANSALKOXYLATION OF 4-NORMAL-DIBUTYLCHLOROSTANNOXY-1-ALKENES AND 4-NORMAL-DIBUTYLCHLOROSTANNOXY-1-ALKYNES WITH ACYL CHLORIDES
No full textCarboxylic acid 1-alkene-4-yl and 1-alkyne-4-yl, esters (RCH(CH2CHCH2)OCOR′ ad RCH(CH2CCH)OCOR′, R = R′ or R ≠ R′ = alkyl or alkenyl group) can be readily prepared in high yields by transalkoxylation reactions between 4-n-dibutylchlorostannoxy-1-alkenes or 4-n-dibutylchlorostannoxy-1-alkynes with acyl chlorides. This represents a general route for preparation of esters containing allyl or propargyl groups
Exploring Media Convergence: Evidence from Italy
Full text linkThe evolution of media and devices is enabling the ubiquitous and multi-device access to media and information, so that a media mutual contamination is in play. New forms of user interactions with media, in which different devices are used simultaneously in different contexts, have emerged. These new interactions are significantly impacting on users' attitudes towards the media and their way of searching and generating content. Such a change, called “media convergence”, has a strong potential impact on marketing and communication processes, but as yet has not been deeply analysed in the literature. This paper presents the outcomes of several studies aimed at exploring media convergence on the demand-side to advance possible implications for marketers and managers
PREPARATION OF ALPHA-ALLENIC AND BETA-ACETYLENIC ALCOHOLS BY TREATMENT OF A MIXTURE OF BU3SNCH=C=CH2 AND RCHO WITH BU2SNCL2 AND WATER
No full textTreatment of a mixture of Bu3SnCHCCH2 and RCHO (R = CH3, C2H5, (CH3)2CH, (CH3)3C) with Bu2SnCl2 in the presence of water gives isomeric mixtures of α-allenic and β-acetylenic alcohols with the α-allenic isomer predominating ( ∼ 75%). Reactions carried out without water give mixtures in which the isomeric ratio between the allenic and acetylenic alcohol varies between 7030 and 5050. In contrast β-acetylenic alcohols predominate when HCHO and α,β-unsaturated aldehydes (R = CH2=CH, CH2=C(CH3), CH3CH=CH, C3H7CH=CH) are used. The stereochemical course of the reactions appear to depend upon the addition and isomerization rates of the Bu2Sn(CH2C=CH)Cl intermediate
Allylstannation V. cis-stereoconvergent sysnthesis of homoallylic alcohols and 4-chloro-2,6-dialkyl-3-methyltetrahydro-pyrans by the addition reaction of 1-buten-3-yldichloro-n-butyltin and aldehydes
No full text1-Buten-3-yl-n-butyldichlorotin, generated in situ by redistribution of (E/Z)-2-butenyltri-n-butyltin and BuSnCl3, reacts readily with neat RCHO (R = CH3, C2H5, (CH3)2CH) at 25°C to give linear alcohols RCH(OH)CH2CHCHCH3 and/or 2,3,4,6-tetrasubstituted tetrahydropyrans, CH2CH(R)OCH(R)CH(CH3)CH-(Cl), which are mainly in the cis-configuration with respect to the CH(CH3)-CH(Cl) bond. When R = (CH3)3C and C6H5, only the homoallylic alcohols are obtained. These cis-stereoconvergent syntheses are explained in terms of kinetic control of the formation of adducts obtained by insertion of one or two aldehyde molecules into the organotin substrat
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