5034-06-0Relevant articles and documents
A new tricrystalline triblock terpolymer by combining polyhomologation and ring-opening polymerization. synthesis and thermal properties
Ladelta, Viko,Zapsas, George,Gnanou, Yves,Hadjichristidis, Nikos
, p. 2450 - 2456 (2019)
New tricrystalline triblock terpolymers, polyethylene-block-poly(ε-caprolactone)-block-poly(L-lactide) (PE-b-PCL-b-PLLA), were synthesized by ROP of ε-caprolactone (CL) and L-lactide (LLA) from linear ω-hydroxyl polyethylene (PE-OH) macroinitiators. The linear PE-OH macroinitiators were prepared by C1 polymerization of methylsulfoxonium methylide (polyhomologation). Tin(II) 2-ethylhexanoate was used as the catalyst for the sequential ROP of CL and LLA in one-pot polymerization at 85?°C in toluene (PE-OH macroinitiators are soluble in toluene at 80?°C). 1H NMR spectra confirmed the formation of PE-b-PCL-b-PLLA triblock terpolymers through the appearance of the characteristic proton peaks of each block. GPC traces showed the increase in the number average molecular weight from PE-OH macroinitiator to PE-b-PCL, and PE-b-PCL-b-PLLA corroborating the successful synthesis. The existence of three crystalline blocks was proved by DSC and XRD spectroscopy.
The boron-catalyzed polymerization of dimethylsulfoxonium methylide. A living polymethylene synthesis
Busch, Brett B.,Paz, Manuel M.,Shea, Kenneth J.,Staiger, Chad L.,Stoddard, Jonathan M.,Walker, James R.,Zhou, Xian-Zhi,Zhu, Huide
, p. 3636 - 3646 (2002)
Trialkyl and aryl organoboranes catalyze the polymerization of dimethylsulfoxonium methylide (1). The product of the polymerization is a tris-polymethylene organoborane. Oxidation affords linear telechelic α-hydroxy polymethylene. The polymer molecular weight was found to be directly proportional to the stoichiometric ratio of ylide/borane, and polydispersities as low as 1.01 - 1.03 have been realized. Although oligomeric polymethylene has been the most frequent synthetic target of this method, polymeric star organoboranes with molecular weights of 1.5 million have been produced. The average turnover frequency at 120 °C in 1,2,4,5-tetrachlorobenzene/toluene is estimated at > 6 x 106 g of polymethylene (mol boron)-1 h-1. The mechanism of the polyhomologation reaction involves initial formation of a zwitterionic organoborane·ylide complex which breaks down in a rate-limiting 1,2-alkyl group migration with concomitant expulsion of a molecule of DMSO. The reaction was found to be first order in the borane catalyst and zero order in ylide. DMSO does not interfere with the reaction. The temperature dependence of the reaction rate yielded the following activation energy parameters (toluene, ΔH? = 23.2 kcal/mol, ΔS? = 12.6 cal deg/mol, ΔG? = 19.5 kcal/mol; THF, ΔH? = 26.5 kcal/mol, ΔS? = 21.5 cal deg/mol, ΔG? = 20.1 kcal/mol).
Preparation method of medetomidine and intermediate thereof
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Paragraph 0064; 0065; 0066; 0067, (2017/08/28)
The invention relates to a preparation method of 2-(2, 3-xylyl)-2-methyloxirane. The method is characterized in that the preparation process includes the following reaction shown as the specification, wherein Y is selected from Cl, Br, I, CH3SO4 or HSO4; alkali is selected from KOH, NaOH, LiOH, CsOH, K2CO3, Li2CO3, Cs2CO3, Na2CO3, EtONa, EtOK, (CH3)2CHONa, (CH3)2CHOK, (CH3)3CONa, (CH3)3COK, NH2Na or NH2K. The invention adopts the synthesis method using the 2-(2, 3-xylyl)-2-methyloxirane critical intermediate to prepare medetomidine.
Process for preparation of trimethylsulfoxonium salts
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, (2008/06/13)
A method for the production of trimethylsulfoxonium salts is described in which trimethylsulfonium salts are oxidized with ruthenium tetroxide in the presence of an inert solvent to form the corresponding trimethylsulfoxonium salts.
Synthesis of an Isolable 4aH-benzocycloheptene, Ethyl 4-Methoxy-4a-methyl-4aH-benzocycloheptene-5-carboxylate, and a Study of its Thermal Rearrangement
Bradbury, Robert H.,Gilchrist, Thomas L.,Rees, Charles W.
, p. 3225 - 3233 (2007/10/02)
A synthesis of ethyl 4-methoxy-4a-methyl-4aH-benzocycloheptene-5-carboxylate (12), the first isolable 4aH-benzocycloheptene, is described.The skeleton is constructed by Cope rearrangement of the divinyl-cyclopropane (8).Further unsaturation is then introduced by the use of dichlorodicyanobenzoquinone to give the tetraenone (10), from which an extended enolate anion is generated by means of sodium hydride in 1,2-dimethoxyethane.O-Methylation of the anion gives the ether (12).At 138 deg C this compound undergoes unimolecular skeletal rearrangement and gives a mixture of three products.It is proposed that these are formed from a common bisnorcaradiene intermediate (17).A new type of rearrangement, which involves the conversion of the bis-norcaradiene (17) into a second bis-norcaradiene by a (?28 + ?4a + ?4a) process, is suggested to explain the formation of the product (19).The methoxy-ester (12) also undergoes 4 + 2 cycloaddition with 4-phenyl-1,2,4-triazolinedione and an acid-catalysed methyl group migration. 4-Methoxy-4a-methyl-4aH-benzocycloheptene (28) has been generated by a analogous route; at room temperature this undergoes skeletal rearrangement, of the same type as observed with the ester (12).
