16225-26-6Relevant articles and documents
Isoselective Lactide Ring Opening Polymerisation using [2]Rotaxane Catalysts
Lim, Jason Y. C.,Yuntawattana, Nattawut,Beer, Paul D.,Williams, Charlotte K.
supporting information, p. 6007 - 6011 (2019/04/03)
Polylactide (PLA) is a fully biodegradable and recyclable plastic, produced from a bio-derived monomer: it is a circular economy plastic. Its properties depend upon its stereochemistry and isotactic PLA shows superior thermal-mechanical performances. Here, a new means to control tacticity by exploiting rotaxane conformational dynamism is described. Dynamic achiral [2]rotaxanes can show high isoselectivity (Pi=0.8, 298 K) without requiring any chiral additives and enchain by a chain end control mechanism. The organocatalytic dynamic stereoselectivity is likely applicable to other small-molecule and polymerization catalyses.
3,5-Di-tert-butylthiobenzoyltriphenylsilane: a versatile spin trapping agent
Alberti, Angelo,Benaglia, Massimo
, p. 151 - 158 (2007/10/02)
3,5-Di-tert-butylthiobenzoyltriphenylsilane (DBTBTPS) has been synthesized and tested as a spin trapping agent for electron spin resonance studies.Upon reaction with a variety of radicals of different nature inside the cavity of the ESR spectrometer.DBTBTPS leads to the observation of rather persistent spectra which in nearly all cases allow the unambiguous identification of the trapped species, DBTBTPS is somewhat less stable than thiobenzoyltriphenylsilane (TBTPS), the unsubstituted thiobenzoyltriphenylsilane; yet, as it affords spin adducts whose spectra are characterized by a smaller number of lines, it may prove more useful than TBTPS itself when dealing with radicals leading to species with a large number of magnetically active nuclei interacting with the unpaired electron.
SELECTIVE MONO- OR DIMETALATION OF ARENES BY MEANS OF SUPERBASIC REAGENTS
Schlosser, Manfred,Choi, Jung Hoon,Takagishi, Sadahito
, p. 5633 - 5648 (2007/10/02)
If employed in tetrahydrofuran, stoichiometric amounts of butyllithium and potassium tert-butoxide react with benzene under clean monometalation.In hexane suspension, however, considerable amounts of meta- and para-disubstituted by-products are obtained (approx. 10percent).They become preponderant if a three-fold excess of the metalating agent is used.Naphthalene leads under the same conditions to a mixture of two mono- and ten di-substituted derivatives. - Alkyl groups, as present in tert-butylbenzene, retard the metalation at both m- and p-positions, while trialkylsilyl groups deactivate only m-position.In either case exclusive monosubstitution occurs. - Perdeuterobenzene undergoes metalation and subsequent electrophilic mono- or disubstitution to afford isotope labeled compounds with moderate, though synthetically attractive yields.The kinetic isotope effects and product ratios can be taken as evidence for aggregate formation at the level of both the superbasic metalating reagent and the organometallic intermediates.
