- Cyclohexyne cycloinsertion in the divergent synthesis of guanacastepenes
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The guanacastepenes are a family of 15 diterpenes that share a common 5-6-7 tricyclic core, which is decorated with quaternary centers, unsaturation, hydroxyl and carbonyl groups. Some of these natural products show interesting antimicrobial potency. Their collective structural and biological features have stirred up vibrant activity among organic chemists. Herein, we disclose an account of our studies toward the synthesis of a number of guanacastepenes. The synthetic strategy relies on the use of cyclohexyne in a cycloinsertion reaction to rapidly construct the guanacastepene core. Isolation of a cyclobutenol as intermediate in the cyclohexyne cycloinsertion provided us with the possibility to study further the reactivity of this metastable compound, and we uncovered novel rearrangements and ring-opening reactions. Stereoselective, late-stage oxidative diversification of the carbon scaffold allowed the synthesis of guanacastepenes N and O and paved the way for the synthesis of guanacastepenes H and D. No strain, no gain! Studies toward the synthesis of the guanacastepene family of diterpenes are presented. The synthetic strategy relies on the use of cyclohexyne as the guanacastepene C-ring, which undergoes cycloinsertion to form the tricyclic carbon scaffold. A host of procedures developed for the diversification of the carbon core allowed the synthesis of guanacastepenes N and O and paved the way for the synthesis of guanacastepenes D and H. Copyright
- Gampe, Christian M.,Carreira, Erick M.
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- BROMINATED FLAME RETARDANTS AND POLYURETHANES CONTAINING THE SAME
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The disclosure includes brominated alkenyl alcohols, their use as a flame retardant in polyurethane and polyurethane foams, and polyurethanes containing the brominated alkenyl alcohols. Compositions, methods, and processes are disclosed. The brominated alkenyl alcohols used as flame retardants in polyurethanes can be generally described by Formula (I), the scope of which is disclosed herein.
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Paragraph 0122; 0124
(2020/07/15)
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- Ynamide Carbopalladation: A Flexible Route to Mono-, Bi- and Tricyclic Azacycles
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Bromoenynamides represent precursors to a diversity of azacycles by a cascade sequence of carbopalladation followed by cross-coupling/electrocyclization, or reduction processes. Full details of our investigations into intramolecular ynamide carbopalladation are disclosed, which include the first examples of carbopalladation/cross-coupling reactions using potassium organotrifluoroborate salts; and an understanding of factors influencing the success of these processes, including ring size, and the nature of the coupling partner. Additional mechanistic observations are reported, such as the isolation of triene intermediates for electrocyclization. A variety of hetero-Diels-Alder reactions using the product heterocycles are also described, which provide insight into Diels-Alder regioselectivity.
- Campbell, Craig D.,Greenaway, Rebecca L.,Holton, Oliver T.,Walker, P. Ross,Chapman, Helen A.,Russell, C. Adam,Carr, Greg,Thomson, Amber L.,Anderson, Edward A.
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supporting information
p. 12627 - 12639
(2015/09/01)
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- Copper-catalyzed allylation of a,a-difluoro-substituted organozinc reagents
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A method for the coupling of organozinc reagents, difluorocarbene, and allylic electrophiles is described. The reaction involves insertion of difluorocarbene into the carbon-zinc bond followed by copper-catalyzed allylic substitution.
- Zemtsov, Artem A.,Kondratyev, Nikolay S.,Levin, Vitalij V.,Struchkova, Marina I.,Dilman, Alexander D.
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p. 818 - 822
(2014/04/03)
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- Process for producing propargyl bromide
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This invention provides a process of producing propargyl bromide in the absence of abase. The process comprises: A) bringing together in a reaction zone under an inert atmosphere and in the absence of a base and in the presence of an inert diluent, a feed of phosphorus tribromide and a separate feed of propargyl alcohol thereby forming a reaction mixture; B) while mechanically agitating the mixture being formed in A), maintaining the temperature of the mixture in the range of about 0° C. to about 25° C. to form a product mixture, and then C) raising the temperature of the product mixture to a temperature in the range of about 40° C. to about 60° C. while stirring the product mixture for a ride period of at least about 2.5 hours. Such process can be conducted as a batch process, as a semi-batch process, or as a continuous process.
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- Process of producing 2-iminothiazoline derivatives and process of producing their intermediates
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There is disclosed a process of producing a 2-iminothiazoline derivative of the general formula [II], characterized in that a thiourea derivative of the general formula [I] is treated with an acid. Also disclosed are a process of producing an N-substituted N-arylcyanamide derivative of the general formula [VI], characterized in that an N-arylcyanamide derivative of the general formula [IV] is reacted with an allyl halide derivative of the general formula [V] in an aprotic polar solvent in the presence of an iodide and an alkali metal carbonate; and a process of producing an N-substituted N-arylthiourea derivative of the general formula [VII], characterized in that an N-substituted N-arylcyanamide derivative of the general formula [VI] obtained as described above is further reacted with a chemical species which generates sulfide ion or hydrogensulfide ion.
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- ALKYLATION OF β-DICARBONYL COMPOUNDS BY 1,2,3-TRIHALOPROPANES AS A METHOD FOR THE PREPARATION OF β-SUBSTITUTED FURANS
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Alkylation of β-dicarbonyl compounds by 1,2,3-trihalides leads to a readily separable mixture of mono- and dialkylation products, and under more rigorous conditions, to 3-substituted 2,4-dimethylfurans.A similar reaction with propargyl bromide leads to furans with a "normal" structure, namely, 2,5-dimethylfurans.
- Akhmedov, Sh. T.,Sadykhov, N. S.,Ismailov, V. M.,Akhundova, M. A.,Sadovaya, N. K.,et al.
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p. 1291 - 1295
(2007/10/02)
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- ORGANIC SYNTHESIS USING HALOBORATION REACTION. I. A SIMPLE AND SELECTIVE SYNTHESIS OF 2-BROMO- AND 2-IODO-1-ALKENES
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B-bromo- or B-iodo-9-borabicyclononane reacts readily with 1-alkynes.Such haloboration reactions proceed through the Markovnikov addition of the X-B moiety to CC bonds and cis fashion.The bromoboration reaction occours chemoselectively at terminal CC bonds but not at internal CC, terminal and internal C=C bonds.The protonolysis of haloboration products with acetic acid gives corresponding 2-bromo- or 2-iodo-1-alkenes in excellent yields.
- Hara, Shoji,Dojo, Hidetaka,Takinami, Satoru,Suzuki, Akira
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p. 731 - 734
(2007/10/02)
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- ALKYLATION OF N-BENZYLIDENEBENZYLAMINE BY HALIDES OF THE PROPARGYL TYPE
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The alkylation of N-benzylidenebenzylamine by halides of the propargyl type under the conditions of interphase catalysis was investigated.It was established that the yield of the γ-acetylenic amine 1-phenyl-1-amino-3-butyne under these conditions amounts to only 5-10 percent, while diphenylethylenediamine is formed with yields of 20-25 percent.Propargylation of N-benzylidenebenzylamine gives a satisfactory yield when the reaction is carried out through the preliminary stage of metallation with observance of the temperature conditions (-70 deg C).
- Mostamandi, A.,Remizova, L.A.,Pavlenkova, A.L.,Favorskaya, I.A.
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p. 850 - 852
(2007/10/02)
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- SUPEROXIDE-MEDIATED DEHYDROHALOGENATION REACTIONS OF THE PYRETHROID PERMETHRIN AND OTHER CHLORINATED PESTICIDES
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Superoxide generated in DMF readily converts the dihalovinyl group of permethrin and related compounds to a haloethynyl moiety and yields major products from elimination reactions of DDT, cis-chlordane, and 1,2-dibromo-3-chloropropane (DBCP).
- Dureja, Prem,Casida, John E.,Ruzo, Luis O.
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p. 5003 - 5004
(2007/10/02)
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- PREPARATION AND SYNTHETIC APPLICATION OF 2-BROMOALLYLTRIMETHYLSILANE AS A 1-HYDROXYMETHYLVINYL ANION EQUIVALENT
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The 1-trimethylsilylmethylvinyl group, as a 1-hydroxymethylvinyl equivalent, was readily introduced to epoxides with the corresponding Grignard reagent derived from 2-bromoallyltrimethylsilane.Obtained 2-(2-hydroxyethyl)-allylsilanes were converted to α-methylene-γ-lactones via diols.
- Nishiyama, Hisao,Yokoyama, Hiroshi,Narimatsu, Shinzo,Itoh, Kenji
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p. 1267 - 1270
(2007/10/02)
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- 1,2-Dibromo-2-cyano-2-(aryl)ethane(propane) antimicrobial compounds
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Antimicrobial compounds of the formulas: STR1 where R1 and R2 are hydrogen; halo; C1-4 alkyl; C1-4 alkoxy; hydroxy; nitro; cyano; or trifluoromethyl; m is 0 or 1; and n is 1 or 2.
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