623-48-3Relevant articles and documents
Infrared spectroscopic studies of the conformation in ethyl α-haloacetates in the vapor, liquid and solid phases
Jassem, Naserallah A.,El-Bermani, Muhsin F.
, p. 213 - 223 (2010)
Infrared spectra of ethyl α-fluoroacetate, ethyl α-chloroacetate, ethyl α-bromoacetate and ethyl α-iodoacetate have been measured in the solid, liquid and vapor phases in the region 4000-200 cm-1. Vibrational frequency assignment of the observed bands to the appropriate modes of vibration was made. Calculations at DFT B3LYP/6-311+G** level, Job: conformer distribution, using Spartan program '08, release 132 was made to determine which conformers exist in which molecule. The results indicated that the first compound exists as an equilibrium mixture of cis and trans conformers and the other three compounds exist as equilibrium mixtures of cis and gauche conformers. Enthalpy differences between the conformers have been determined experimentally for each compound and for every phase. The values indicated that the trans of the first compound is more stable in the vapor phase, while the cis is the more stable in both the liquid and solid phases. In the other three compounds the gauche is more stable in the vapor and liquid phases, while the cis conformer is the more stable in the solid phase for each of the second and third compound, except for ethyl α-iodoacetate, the gauche conformer is the more stable over the three phases. Molar energy of activation Ea and the pseudo-thermodynamic parameters of activation ΔH?, ΔS? and ΔG? were determined in the solid phase by applying Arrhenius equation; using bands arising from single conformers. The respective Ea values of these compounds are 5.1 ± 0.4, 6.7 ± 0.1, 7.5 ± 1.3 and 12.0 ± 0.6 kJ mol-1. Potential energy surface calculations were made at two levels; for ethyl α-fluoroacetate and ethyl α-chloroacetate; the calculations were established at DFT B3LYP/6-311+G** level and for ethyl α-bromoacetate and ethyl α-iodoacetate at DFT B3LYP/6-311G* level. The results showed no potential energy minimum exists for the gauche conformer in ethyl α-fluoroacetate.
A catalytic, Me2Zn-mediated, enantioselective reformatsky reaction with ketones
Cozzi, Pier Giorgio
, p. 2951 - 2954 (2006)
(Chemical Equation Presented) Kill two birds with one ... Salen! A catalytic and practical Me2Zn-mediated enantioselective Reformatsky reaction promoted by [ClMn(salen)] with a ketone as the electrophile is presented (see scheme). The broad scope and simple nature of this procedure, which allows the use of commercially available starting materials and leads to useful building blocks containing quaternary stereocenters, make it extremely attractive. (salen = N,N′-ethylene-bis(salicylideneamine).).
Forskolin Editing via Radical Iodo- A nd Hydroalkylation
Pruteanu, Elena,Tappin, Nicholas D. C.,G?rbu, Vladilena,Morarescu, Olga,Dénès, Fabrice,Kulci?ki, Veaceslav,Renaud, Philippe
, p. 1247 - 1261 (2021)
The modification of highly oxygenated forskolin as well as manoyl and epi-manoyl oxide, two less functionalized model substrates sharing the same polycyclic skeleton, via intermolecular carbon-centered radical addition to the vinyl moiety has been investigated. Highly regio- A nd reasonably stereoselective iodine atom transfer radical addition (ATRA) reactions were developed. Unprotected forskolin afforded an unexpected cyclic ether derivative. Protection of the 1,3-diol as an acetonide led the formation of the iodine ATRA product. Interestingly, by changing the mode of initiation of the radical process, in situ protection of the forskolin 1,3-diol moiety as a cyclic boronic ester took place during the iodine ATRA process without disruption of the radical chain process. This very mild radical-mediated in situ protection of 1,3-diol is expected to be of interest for a broad range of radical and non-radical transformations. Finally, by using our recently developed tert-butyl?-catechol-mediated hydroalkylation procedure, highly efficient preparation of forskolin derivatives bearing an extra ester or sulfone group was achieved.
CIBALACKROT RED DYE COMPOUNDS AND METHODS OF USE IN ORGANIC SOLID-STATE LASERS AND OPTO-ELECTRONIC APPLICATIONS
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Paragraph 00203, (2021/04/10)
Cibalackrot red dye monomer and dimer compounds of formulae (I) and (II) are disclosed as well as combination of the Cibalackrots with host matrices such as a mixed host of mCP and HBT. Use of the Cibalackrots as laser dyes as well in organic solid-state lasers and opto-electronic applications is also described.
Methyl Radical Initiated Kharasch and Related Reactions
Tappin, Nicholas D. C.,Renaud, Philippe
supporting information, p. 275 - 282 (2020/12/07)
An improved procedure to run halogen atom and related chalcogen group transfer radical additions is reported. The procedure relies on the thermal decomposition of di-tert-butylhyponitrite (DTBHN), a safer alternative to the explosive diacetyl peroxide, to produce highly reactive methyl radicals that can initiate the chain process. This mode of initiation generates byproducts that are either gaseous (N2) or volatile (acetone and methyl halide) thereby facilitating greatly product purification by either flash column chromatography or distillation. In addition, remarkably simple and mild reaction conditions (refluxing EtOAc during 30 minutes under normal atmosphere) and a low excess of the radical precursor reagent (2 equivalents) make this protocol particularly attractive for preparative synthetic applications. This initiation procedure has been demonstrated with a broad scope since it works efficiently to add a range of electrophilic radicals generated from iodides, bromides, selenides and xanthates over a range of unactivated terminal alkenes. A diverse set of radical trap substrates exemplifies a broad functional group tolerance. Finally, di-tert-butyl peroxyoxalate (DTBPO) is also demonstrated as alternative source of tert-butoxyl radicals to initiate these reactions under identical conditions which gives gaseous by-products (CO2). (Figure presented.).
Enantioselective Hydroazidation of Trisubstituted Non-Activated Alkenes
Meyer, Daniel,Renaud, Philippe
supporting information, p. 10858 - 10861 (2017/08/30)
A one-pot procedure for the enantioselective hydroazidation of non-activated trisubstituted alkenes is described. Hydroboration with monoisopinocampheylborane (IpcBH2) provides dialkylboranes that are in situ selectively converted into monoalkyl-substituted catecholboranes; these undergo radical azidation upon treatment with benzenesulfonyl azide and a radical initiator. Enantiomerically enriched azides were thus obtained in yields of 59–81 % and enantioselectivities of up to 94:6 e.r. (98:2 e.r. if the intermediate dialkylborane is purified by crystallization). A rapid access to enantiomerically pure (+)-rodocaine is also described. The use of other arenesulfonyl radical traps enables enantioselective hydroallylation, hydrosulfanylation, and hydrobromination reactions with yields of 71–86 %.
Decarboxylative (4+1) Oxidative Annulation of Malonate Monoesters with 2-Vinylpyridine Derivatives
Tang, Shan,Gao, Xinlong,Lei, Aiwen
supporting information, p. 2878 - 2882 (2016/09/16)
A novel N-iodosuccinimide-mediated decarboxylative (4+1) oxidative annulation between 2-vinylpyridine derivatives and malonate monoesters was developed. It offers a new way to construct indolizine derivatives by utilizing malonate monoesters as a C1unit. The alkyl 2,2-diiodoacetate was found to be the active reaction intermediate during the transformation. (Figure presented.).
The synthesis and analysis of advanced lignin model polymers
Lancefield,Westwood
supporting information, p. 4980 - 4990 (2015/11/16)
If the lignin-first biorefinery concept becomes a reality, high quality lignins close in structure to native lignins will become available in large quantities. One potential way to utilise this renewable material is through depolymerisation to aromatic chemicals. This will require the development of new chemical methods. Here, we report the synthesis and characterisation of advanced lignin model polymers to be used as tools to develop these methods. The controlled incorporation of the major linkages in lignin is demonstrated to give complex hardwood and softwood lignin model polymers. These polymers have been characterised by 2D HSQC NMR and GPC analysis and have been compared to isolated lignins.
Systematic study on alkyl iodide initiators in living radical polymerization with organic catalysts
Lei, Lin,Tanishima, Miho,Goto, Atsushi,Kaji, Hironori,Yamaguchi, Yu,Komatsu, Hiroto,Jitsukawa, Takuya,Miyamoto, Michihiko
, p. 6610 - 6618 (2015/02/19)
Several low-molar-mass alkyl iodides were studied as initiating dormant species in living radical polymerization with organic catalysts. Primary, secondary, and tertiary alkyl iodides with different stabilizing groups (ester, phenyl, and cyano groups) were systematically studied for the rational design of initiating alkyl iodides. The activation rate constants of these alkyl iodides were experimentally determined for quantitative comparison. These alkyl iodides were used in the polymerizations of methyl methacrylate and butyl acrylate to examine their initiation ability in these polymerizations. A telechelic polymer was prepared using an alkyl iodide with a functional group. Alkyl iodides with multi-initiating sites were also studied.
N,N′-Dialkylaminoalkylcarbonyl (DAAC) prodrugs and aminoalkylcarbonyl (AAC) prodrugs of 4-hydroxyacetanilide and naltrexone with improved skin permeation properties
Devarajan-Ketha,Sloan
body text, p. 4078 - 4082 (2011/08/06)
N,N′-Dialkylaminoalkylcarbonyl (DAAC) and aminoalkylcarbonyl (AAC) prodrugs of phenolic drugs acetaminophen (APAP) and naltrexone (NTX) are reported. The effects of incorporation of a basic amine group into the promoiety of an acyl prodrug of a phenolic drug on its skin permeation properties are also presented. DAAC-APAP prodrugs were synthesized via a three-step procedure starting with haloalkylcarbonyl esters which were reacted with five different amines: dimethylamine, diethylamine, dipropylamine, morpholine, and piperidine. The spacing between the amino group and the carbonyl group of the acyl group was 1-3 CH2. After the hydrolysis of the ester, the carboxylic acid product was subsequently coupled with the parent drug via a dicyclohexyl carbodiimide (DCC) mediated coupling to yield the DAAC-APAP-HCl prodrugs in excellent yields. The AAC prodrugs were synthesized using commercially available Boc-protected amino acids using DCC or EDCI as coupling agents. The yields of the prodrugs synthesized using these two different methods have been compared. Half-lives (t1/2) of a few members of the DAAC and AAC series were measured in buffer (pH 6.0, 20 mM). The members evaluated in hydrolysis experiments exhibit a t1/2 range of 15-113 min. Among AAC-APAP prodrugs, the isopropyl group in valinate-APAP-HCl exerted a steric effect that increased the t1/2 value for this prodrug compared to alaninate-APAP-HCl or prolinate-APAP-HCl. The 2-morpholinylacetate-APAP prodrug was able to achieve twice the flux of APAP in in vitro diffusion cell experiments through hairless mouse skin.
