- A Catalytic Approach for Enantioselective Synthesis of Homoallylic Alcohols Bearing a Z-Alkenyl Chloride or Trifluoromethyl Group. A Concise and Protecting Group-Free Synthesis of Mycothiazole
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A protecting group-free strategy is presented for diastereo- and enantioselective routes that can be used to prepare a wide variety of Z-homoallylic alcohols with significantly higher efficiency than is otherwise feasible. The approach entails the merger of several catalytic processes and is expected to facilitate the preparation of bioactive organic molecules. More specifically, Z-chloro-substituted allylic pinacolatoboronate is first obtained through stereoretentive cross-metathesis between Z-crotyl-B(pin) (pin = pinacolato) and Z-dichloroethene, both of which are commercially available. The organoboron compound may be used in the central transformation of the entire approach, an α- and enantioselective addition to an aldehyde, catalyzed by a proton-activated, chiral aminophenol-boryl catalyst. Catalytic cross-coupling can then furnish the desired Z-homoallylic alcohol in high enantiomeric purity. The olefin metathesis step can be carried out with substrates and a Mo-based complex that can be purchased. The aminophenol compound that is needed for the second catalytic step can be prepared in multigram quantities from inexpensive starting materials. A significant assortment of homoallylic alcohols bearing a Z-F3C-substituted alkene can also be prepared with similar high efficiency and regio-, diastereo-, and enantioselectivity. What is more, trisubstituted Z-alkenyl chloride moiety can be accessed with similar efficiency albeit with somewhat lower α-selectivity and enantioselectivity. The general utility of the approach is underscored by a succinct, protecting group-free, and enantioselective total synthesis of mycothiazole, a naturally occurring anticancer agent through a sequence that contains a longest linear sequence of nine steps (12 steps total), seven of which are catalytic, generating mycothiazole in 14.5% overall yield.
- Morrison, Ryan J.,Van Der Mei, Farid W.,Romiti, Filippo,Hoveyda, Amir H.
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supporting information
p. 436 - 447
(2020/01/09)
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- Direct synthesis of Z-alkenyl halides through catalytic cross-metathesis
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Olefin metathesis has had a large impact on modern organic chemistry, but important shortcomings remain: for example, the lack of efficient processes that can be used to generate acyclic alkenyl halides. Halo-substituted ruthenium carbene complexes decompose rapidly or deliver low activity and/or minimal stereoselectivity, and our understanding of the corresponding high-oxidation-state systems is limited. Here we show that previously unknown halo-substituted molybdenum alkylidene species are exceptionally reactive and are able to participate in high-yielding olefin metathesis reactions that afford acyclic 1,2-disubstituted Z-alkenyl halides. Transformations are promoted by small amounts of a catalyst that is generated in situ and used with unpurified, commercially available and easy-to-handle liquid 1,2-dihaloethene reagents, and proceed to high conversion at ambient temperature within four hours. We obtain many alkenyl chlorides, bromides and fluorides in up to 91 per cent yield and complete Z selectivity. This method can be used to synthesize biologically active compounds readily and to perform site- and stereoselective fluorination of complex organic molecules.
- Koh, Ming Joo,Nguyen, Thach T.,Zhang, Hanmo,Schrock, Richard R.,Hoveyda, Amir H.
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p. 459 - 465
(2016/04/05)
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- Synthesis of γ-functionalized allyltrichlorosilanes and their application in the asymmetric allylation of aldehydes
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Isomerically pure trans-and cis-γ-bromoallyltrichlorosilanes 4 and 5 have been synthesized and shown to react with aromatic aldehydes 1 in the presence of Lewis-basic catalysts (e.g., DMF) to produce the corresponding anti-and syn-allylbromohydrins 8 and 9, respectively, as single diastereoisomers. With BINAPO 25 as a chiral catalyst, promising enantioselectivity (≤50% ee) has been attained.
- Malkov, Andrei V.,MacDonald, Claire,Koovsky, Pavel
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body text
p. 1173 - 1175
(2010/11/02)
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- Cr(Salen)-catalyzed addition of 1,3-dichloropropene to aromatic aldehydes. A simple access to optically active vinyl epoxides.
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[reaction: see text]. Chiral Cr(Salen) complex (1) prepared in situ from CrCl3 promotes the enantioselective addition of 1,3-dichloropropene to aromatic aldehydes in the presence of Mn as the stoichiometric reductant and Me3SiCl as a scavenger. The result
- Bandini,Cozzi,Melchiorre,Morganti,Umani-Ronchi
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p. 1153 - 1155
(2007/10/03)
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- Either γ-syn- Or γ-anti-selective palladium-catalysed carbonyl allylation by mixed (E)- and (Z)-l,3-dichloropropene with tin(II) halides
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Palladium-catalysed carbonyl allylations by mixed (E)- and (Z)-1,3-dichloropropene with SnI2-Bu4NI and SnCl2 diastereoselectively produce syn and anti 1-substituted 2-chlorobut-3-en-1-ols, respectively. These are transform
- Masuyama, Yoshiro,Ito, Akihiro,Kurusu, Yasuhiko
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p. 315 - 316
(2007/10/03)
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- Indium-mediated reaction of 1,3-dichloro- and 1,3-dibromopropenes with carbonyl compounds. Generation of novel 3,3-diindiopropene
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Indium-mediated reaction of 1,3-dichloropropene with aldehyde gave syn-chlorohydrin predominantly. A similar reaction of 1,3-dibromopropene gave vinyloxirane and homoallyl alcohol; the former is formed from γ-bromoallylindium via the corresponding bromohydrin, and the latter is considered to be derived from a unique allylic diindium reagent, 3,3-diindiopropene.
- Araki, Shuki,Hirashita, Tsunebisa,Shimizu, Hidetaka,Yamamura, Hatsuo,Kawai, Masao,Butsugan, Yasuo
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p. 8417 - 8420
(2007/10/03)
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- Reaction of α-halo organoindium reagents with carbonyl compounds and electron-deficient alkenes
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A variety of α-halo organoindium reagents were prepared in situ from the reaction of gem-dihalo compounds with indium metal, and their reactions with carbonyl compounds and electron-deficient alkenes were examined. The reactions of simple 1,1-diiodoalkanes with indium metal gave no defined products but benzal iodide gave stilbene in a moderate yield. α-Halo organoindium reagents derived from α,α-dibromo carbonyl compounds gave oxiranes and cyclopropanes upon the reactions with aldehydes and alkenes, respectively. 3,3-Dichloropropenes reacted with aldehydes in the presence of indium metal to give the corresponding chlorohydrins and/or homoallylalcohols, depending on the structures of both the dichloropropenes and aldehydes employed.
- Araki, Shuki,Hirashita, Tsunehisa,Shimizu, Ken,Ikeda, Takahiro,Butsugan, Yasuo
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p. 2803 - 2816
(2007/10/03)
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- Reactions of α-haloallyllithium derivatives with carbon, silicon, tin or boron halides and carbonyl compounds
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A series of allylic halides have been converted into their α-carbanions with strong lithium bases, using different techniques.These have been compared in their reaction with various electrophiles leading to functionally substituted allyl derivatives.The influence of the counterion on the regio- and stereoselectivity has been investigated. allylic halides / α-halocarbanions / allylsilanes / allyltin derivatives / α-chlorohydrins / vinylepoxides / diastereoselectivity
- Julia, Marc,Verpeaux, Jean-Noel,Zahneisen, Thomas
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p. 539 - 554
(2007/10/02)
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- Chloroallyl Anion: Highly Regio- and Diastereoselective α-Addition of Chloroallyl Zinc Reagent to Carbonyl Compounds
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The chloroallyl zinc reagent generated insitu by deprotonation of allyl chloride in the presence of lithium diisopropylamide and zinc chloride undergoes highly regio- and diastereoselective α-addition to carbonyl compounds to give syn chlorohydrins which
- Mallaiah, K.,Satyanarayana, J.,Ila, H.,Junjappa, H.
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p. 3145 - 3148
(2007/10/02)
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- A mild convenient Barbier-type allylation of aldehydes to homoallylic alcohols via iodide ion promoted stannylation of allylic bromides and chlorides with tin(II) chloride
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Barbier-type allylation of aldehydes with allylic bromides and tin(II) chloride dihydrate is largely accelerated by adding stoichiometric or substoichiometric amounts of sodium iodide. This method has some merits such as lower temperature, shorter reaction time and/or more choices of solvents for the reaction. Moreover, the activation by the iodide ion enables the use of relatively unreactive allylic chlorides of various structural types (e.g., 3-chloro-2-chloromethylpropene as an isobutene dianion equivalent) and, thus, expands synthetic applicability of this reaction. The major role of the iodide salt is attributed to the in situ generation of the corresponding allylic iodide.
- Imai,Nishida
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p. 395 - 399
(2007/10/02)
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- HETERO-ATOM SUBSTITUTED CHROMIUM ALLYLS: SYNTHETIC STUDIES ON NEOCARZINOSTATIN CHROMOPHORE ANALOGUES
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The preparation and reactions of hetero-atom substituted chromium allyls derived from 7a, 7b, 12, and 15 are described in connection with studies on the synthesis of neocarzinostatin analogues.
- Wender, Paul A.,Wisniewski Grissom, Janet,Hoffmann, Ursula,Mah, Robert
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p. 6605 - 6608
(2007/10/02)
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- FACILE PREPARATION OF γ-CHLORO-SUBSTITUTED ALLYLMETALLIC REAGENTS AND THEIR REACTIONS. STEREOSELECTIVE ACCESS TO CIS-VINYLOXIRANES
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The title compounds are readily prepared from metallated allyl chloride and organotin chloride or organoaluminum chloride.After treatment with a base, they react with aldehydes in highly regio- and diastereo-selective modes, giving cis-vinyloxiranes selectively.Keywords -- lithiated allyl chloride; Z-γ-chloroallyltrimethyltin; γ-chloroallyldiethylaluminum; stereoselective synthesis; syn-chlorohydrin; cis-vinyloxirane
- Hosomi, Akira,Kohra, Shinya,Tominaga, Yoshinori,Ando, Masamoto,Sakurai, Hideki
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p. 3058 - 3061
(2007/10/02)
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- A SIMPLE, STEREOSELECTIVE, ROOM-TEMPERATURE SYNTHESIS OF CIS VINYLOXIRANES AND TRANS 1-PHENYL-1,3-BUTADIENE
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The organotin reagent from 1-chloro-3-iodoprop-1-ene and SnCl2 in dimethylformamide reacted with aldehydes by its chlorine-substituted carbon atom.Treatment with NaOMe then gave cis vinyloxiranes with good stereoselectivity.Benzaldehyde and 1-bromo-3-iodo
- Auge, Jacques,David, Serge
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p. 4009 - 4012
(2007/10/02)
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