4165-86-0Relevant academic research and scientific papers
Triphosgene and DMAP as Mild Reagents for Chemoselective Dehydration of Tertiary Alcohols
Ganiu, Moshood O.,Cleveland, Alexander H.,Paul, Jarrod L.,Kartika, Rendy
supporting information, p. 5611 - 5615 (2019/08/01)
The utility of triphosgene and DMAP as mild reagents for chemoselective dehydration of tertiary alcohols is reported. Performed in dichloromethane at room temperature, this reaction is readily tolerated by a broad scope of substrates, yielding alkenes preferentially with the (E)-geometry. While formation of the Hofmann products is generally favored, a dramatic change in alkene selectivity toward the Zaitzev products is observed when the reaction is carried out in dichloroethane at reflux.
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 %.
Enantioselective Oxidative Rearrangements with Chiral Hypervalent Iodine Reagents
Brown, Michael,Kumar, Ravi,Rehbein, Julia,Wirth, Thomas
supporting information, p. 4030 - 4035 (2016/03/16)
A stereoselective hypervalent iodine-promoted oxidative rearrangement of 1,1-disubstituted alkenes has been developed. This practically simple protocol provides access to enantioenriched α-arylated ketones without the use of transition metals from readily
Iron-catalyzed alkenylation of Grignard reagents by enol phosphates
Cahiez, Gerard,Gager, Olivier,Habiak, Vanessa
experimental part, p. 2636 - 2644 (2009/04/07)
Stereoselective preparation of trisubstituted olefins can be easily performed from an Z/E-mixture of enol phosphates by reacting only the E-isomer with a Grignard reagent in the presence of Fe(acac)3. This procedure combines a kinetic differentiation and a stereoselective reaction. The coupling is very chemoselective in the presence of an alkyl chloride, an ester, a ketone or a nitrile. Georg Thieme Verlag Stuttgart.
A sterically modified (salen)chromium(III) complex - An efficient catalyst for high-pressure asymmetric allylation of aldehydes
Kwiatkowski, Piotr,Cha?adaj, Wojciech,Jurczak, Janusz
, p. 2301 - 2304 (2007/10/03)
A novel (salen)chromium(III) catalyst with a modified salen ligand was synthesised in a simple way starting from readily available precursors. High-pressure allylation reaction of aromatic and aliphatic aldehydes with allyltributyltin upon application of
Heterodimerization of Olefins. 1. Hydrovinylation Reactions of Olefins That Are Amenable to Asymmetric Catalysis
RajanBabu,Nomura, Nobuyoshi,Jin, Jian,Nandi, Malay,Park, Haengsoon,Sun, Xiufeng
, p. 8431 - 8446 (2007/10/03)
Through a systematic examination of ligand and counterion effects, new protocols for a nearly quantitative and highly selective codimerization of ethylene and various functionalized vinylarenes have been discovered. In a typical reaction, 4-bromostyrene and ethylene undergo codimerization in the presence of 0.0035 equiv each of [(allyl)NiBr]2, triphenylphosphine, and AgOTf in CH2Cl2 at -56 °C to give 3-(4-bromophenyl) -1-butene in >98% yield and selectivity. Corresponding reactions with [(allyl)PdX]2 are much less efficient and less selective and may require further optimization before a viable system can be identified. Another useful protocol that gives comparable yield and selectivity involves the use of a single-component catalyst prepared from allyl 2-diphenylphosphinobenzoate, Ni(COD)2, and (C6F5)3B. Recognition of a synergistic relationship between a chiral hemilabile ligand (for example, (R)-2-methoxy-2′-diphenylphosphino-1,1′-binaphthyl, MOP) and a highly dissociated counteranion (BARF or SbF6) in an enantioselective version of the Ni-catalyzed reaction raises the prospects of developing a practical route for the synthesis of 3-arylbutenes. Several pharmaceutically relevant compounds, including widely used 2-arylpropionic acids, can be synthesized from these key intermediates. This reaction appears to be quite general. Synthesis of several new 2-diphenylphosphino-1,1-binaphthyl derivatives, prepared to probe the effect of hemilabile coordination on the efficiency and selectivity of the reaction, are also described.
A general and stereoselective method for synthesis of tri- and tetrasubstituted alkenes
Macia?giewicz,Dybowski,Skowrońska
, p. 6057 - 6066 (2007/10/03)
A convenient, general and stereoselective synthesis of trisubstituted alkenes and tetrasubstituted alkenes containing a cyanide function as well as trisubstituted episulphides have been elaborated. Methodology described for the preparation of these compounds is based on the corresponding readily available selenophosphates 1 and thiophosphates 2.
Lewis Acid-Promoted Disproportionation Reaction of Aromatic Vinyl Ethers and Acetals and Its Application to the Synthesis of Paracotoin
Gong, Young Dae,Tanaka, Hiroko,Iwasawa, Nobuharu,Narasaka, Koichi
, p. 2181 - 2185 (2007/10/03)
Aromatic vinyl ethers and acetals underwent a novel addition-fragmentation reaction affording olefins and esters in the presence of a Lewis acid. This reaction was applied to intramolecular cyclization reaction, giving five or six membered ring compounds in good yields. Paracotoin, an intermediate in the biosynthesis of shikimic acid, was synthesized using this cyclization reaction as the key step.
Benzotriazole-mediated synthesis of α-di- and α-trisubstituted ethers and sulfides
Katritzky,Jurczyk,Szajda,Shcherbakova,Lam
, p. 499 - 504 (2007/10/02)
Ethylaryl- and diethylaryl(benzotriazol-1-yl)methanes, obtained by mono- or dialkylation of substituted (benzotriazol-1-ylmethyl)benzenes, react with sodium alkoxides, phenol and thiophenol to yield the corresponding α-di- and α-trisubstituted ethers and
Regiospecific and Stereospecific Synthesis of E- and Z-Trisubstituted Alkenes via 2,2-Disubstituted Vinylsilanes
Chou, Shang-Shing P.,Kuo, Hwei-Lon,Wang, Chung-Jen,Tsai, Chung-Ying,Sun, Chung-Ming
, p. 868 - 872 (2007/10/02)
Treatment of terminal alkynes 1 with the organocopper reagents derived from Grignard reagents, cuprous iodide, and lithium bromide (molar ratio 2:1:2) at low temperature followed by the addition of chlorotrimethylsilane gave the 2,2-disubstituted vinylsilanes 2 with complete regio- and stereospecificity (syn addition).Electrophilic substitution of 2 with ICl, Br2, and acetyl chloride gave the corresponding vinyl iodides, bromides, and α,β-unsaturated ketones 5 with retention of configuration.Epoxidation of 2 with MCPBA gave the epoxy silanes 6, which upon treatment with concentrated HX and BF3*Et2O gave the vinyl halides 7 with net inversion of configuration.If the epoxy silanes 6 were first converted to the β-hydroxy silanes 8 by Gilman's reagents, either E- or Z-trisubstituted alkenes 9 and 10 could be obtained by treatment with acid or base.Vinyl halides 7 could also be stereoselectively converted to other functionalities via the vinyllithium intermediates.
