1575-71-9Relevant academic research and scientific papers
Synthesis of a spirocyclic seco structure of the principal vetiver odorant Khusimone
Kraft, Philip,Denizot, Natacha
, p. 49 - 58 (2013)
The three-dimensional structure of tricyclic compounds with a zero-bridge to one bridgehead atom is determined by the underlying spirocyclic framework. (-)-Khusimone (1), the principal odorant of vetiver oil (content up to 2 %), is such a tricyclic norsesquiterpene, and dissection of the 7,8-bond between the methylene and the gem-dimethyl unit of 1 results in a spirocycle extending over an almost identical molecular volume and shape. Given that the vetiver rule postulates that one α-branched carbonyl osmophore in a certain spatial distance to a bulky moiety is responsible for the odor of vetiver, a 7,8-seco structure of 1 could prove or disprove these structural requirements. Therefore, (4R*,5R*)-7-isopropyl-4-vinylspiro[4.4]nonan-1-one [(4R*,5R*)-2] was synthesized in a 10-step synthetic sequence commencing with Steglich esterification of allyl alcohol (15) and isovaleric acid (14). Ireland-Claisen rearrangement of the formed allyl isovalerate (16) with subsequent lithium aluminum hydride reduction of resulting γ,δ-unsaturated acid 18, Appel bromination of corresponding alcohol 19, and ozonolysis provided 4-bromo-3-isopropylbutanal (23) in 19 % overall yield as a building block for the projected spiroannulation reactions. Although attempts on cyclopentanone (7) failed, cyclopent-2-en-1-one, via its TMS-trapped lithium 3-vinylcyclopent-1-enolate 12, turned out to be a successful starting material. Evans' variant of the Mukaiyama aldol reaction with 1-trimethylsiloxy-3-vinylcyclopent-1-ene (12) in the presence of BF 3·OEt2, followed by palladium-catalyzed conjugate tin hydride reduction of resulting enone 28 provided 2-(4′-bromo-3′- isopropylbutyl)-3-vinylcyclopentanone (29) in 50 % overall yield as the anlation precursor. LDA-mediated 5-exo-tet cyclization of 29 concluded the synthesis of the racemic 7,8-seco-/6-epi-7,8-secokhusimone mixture (4R*,5R*)-2, which possessed a floral, rosy, green, geranium-like odor with a threshold of 42.0 ng L-1 air, which is 10 times less intense than that of (-)-khusimone (1). Most importantly, seco structure (4R*,5R*)-2 did not display any woody nor any vetiver character, which proves the postulated vetiver rule wrong. Dissecting the bond between the methylene and the gem-dimethyl unit of khusimone leads to a spirocycle of almost identical shape, which was synthesized by 1,4-conjugate addition of a vinyl Gilman reagent, Mukaiyama aldol condensation of a bromo aldehyde prepared by Ireland-Claisen rearrangement of allyl isovalerate, and subsequent cyclization. Copyright
Radical Aryl Migration from Boron to Carbon
Daniliuc, Constantin G.,Mück-Lichtenfeld, Christian,Studer, Armido,Wang, Dinghai
supporting information, p. 9320 - 9326 (2021/07/19)
Radical aryl migration reactions represent a unique type of organic transformations that involve the intramolecular migration of an aryl group from a carbon or heteroatom to a C- or heteroatom-centered radical through a spirocyclic intermediate. Various elements, including N, O, Si, P, S, Sn, Ge, and Se, have been reported to participate in radical aryl migrations. However, radical aryl migration from a boron center has not been reported to date. In this communication, radical 1,5-aryl migration from boron to carbon in aryl boronate complexes is presented. C-radicals readily generated through radical addition onto alkenyl aryl boronate complexes are shown to engage in 1,5-aryl migration reactions to provide 4-aryl-alkylboronic esters. As boronate complexes can be generatedin situby the reaction of alkenylboronic acid esters with aryl lithium reagents, the aryl moiety is readily varied, providing access to a series of arylated products starting from the same alkenylboronic acid ester via divergent chemistry. Reactions proceed with high diastereoselectivity under mild conditions, and also the analogous 1,4-aryl shifts are feasible. The suggested mechanism is supported by DFT calculations.
Synthesis method of apronal
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, (2019/12/11)
Belonging to the technical field of drug synthesis, the invention discloses a synthesis method of apronal. The method adopts commercial raw material isopropyl malonate diester as the starting raw material for reaction with allyl bromide or allyl chloride under an alkaline condition by one-pot process to generate dimethyl allyl isopropylmalonate, then hydrolysis is carried out to generate allyl isopropylmalonic acid, which is subjected to thermal decomposition to be further converted into acyl chloride for reaction with urea, thus obtaining apronal. The synthetic route adopted by the inventiononly needs two or three steps, the whole process is in simple in operation, the materials are easily available, the cost is low, and the yield is high, therefore the method is suitable for industrialproduction.
Synthesis method of apronal
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Paragraph 0027-0030, (2018/04/01)
The invention discloses a synthesis method of apronal. The synthesis method takes isopentanoic acid or isopentanoate which is commercially cheap and available as a synthesis raw material and comprises the following steps: enabling the synthesis raw material and allyl bromide to react under an alkaline condition to generate 2-isopropyl-4-pentenoic acid or 2-isopropyl-4-pentanoate; hydrolyzing the 2-isopropyl-4-pentanoate under the alkaline condition to generate the 2-isopropyl-4-pentenoic acid; then transforming the 2-isopropyl-4-pentenoic acid into acyl chloride and enabling the acyl chloride to react with urea to obtain the apronal. According to the synthesis method disclosed by the invention, a synthesis route can realize medium-scale preparation of the apronal, with the need of two-step or three-step chemical transformation; the whole synthesis route is simple and efficient, simple and convenient to operate, low in cost and high in yield so that the synthesis method is suitable for large-quantity synthesis of the apronal.
N -Boc amines to oxazolidinones via Pd(II)/bis-sulfoxide/br?nsted acid Co-catalyzed allylic C-H oxidation
Osberger, Thomas J.,White, M. Christina
supporting information, p. 11176 - 11181 (2014/08/18)
A Pd(II)/bis-sulfoxide/Br?nsted acid catalyzed allylic C-H oxidation reaction for the synthesis of oxazolidinones from simple N-Boc amines is reported. A range of oxazolidinones are furnished in good yields (avg 63%) and excellent diastereoselectivities (avg 15:1) to furnish products regioisomeric from those previously obtained using allylic C-H amination reactions. Mechanistic studies suggest the role of the phosphoric acid is to furnish a Pd(II)bis-sulfoxide phosphate catalyst that promotes allylic C-H cleavage and π-allylPd functionalization with a weak, aprotic oxygen nucleophile and to assist in catalyst regeneration.
Intramolecular formal [4+2] cycloaddition of 3-ethoxycyclobutanones and alkenes
Matsuo, Jun-Ichi,Sasaki, Shun,Hoshikawa, Takaya,Ishibashi, Hiroyuki
supporting information; scheme or table, p. 934 - 936 (2010/06/12)
Intramolecular formal [4+2] cycloaddition between 3-ethoxycyclobutanones and a carbon-carbon double bond to the corresponding bicyclo[4.n.0]alkan-2-one derivatives proceeded effectively by using ethylaluminium dichloride. The Royal Society of Chemistry 20
Intermolecular free radical reactions on solid support. Allylation of esters
Sibi, Mukund P.,Chandramouli, Sithamalli V.
, p. 8929 - 8932 (2007/10/03)
The first examples of intermolecular free radical allylation reactions on solid support are reported. The allylation proceeds in good chemical efficiency with a variety of substrates as well as allylating agents. Control experiments indicate that the polymer matrix is inert to the reaction conditions.
A CATALYTIC ROLE OF Cu(II) FOR CONJUGATE ADDITION OF GRIGNARD REAGENTS. A COMPLETELY DIFFERENT BEHAVIOR FROM ORGANOCUPRATES
Aoki, Youji,Kuwajima, Isao
, p. 7457 - 7460 (2007/10/02)
Different from lithium dialkycuprates, Cu(II) catalyzed conjugate addition of Grignard reagents to allylic esters of α,β-unsaturated carboxylates has been effected in the presence of TMS-Cl, and the resulting allyl silyl keteneacetals further undergo rearrangement to afford 2-allyl 3-alkyl carboxylic acids in good yields.
Effects of α-Substitution on the Rate of Chloromercuriolactonization of Phenyl Esters of γδ-Unsaturated Acids
de Almeida, Maria I.,do Amaral, Antonia T.,do Amaral, Luciano
, p. 1953 - 1958 (2007/10/02)
Second-order rate constants for the reaction of several phenyl esters of α-alkyl- and/or α-aryl-substituted allyacetic acids with mercury(II) chloride have been determined in 50percent aqueous ethanol.It was found that α-substitution increases the rate of reaction.The rate constants can be correlated with the dual substituent parameter expressions (i) and (ii).In the systems studied the steric coefficient is much larger than the polar one, suggesting that the effect of the substituents on the rate of the reaction is essentially steric in nature, with a small additional contribution from the polar effect. log k2 = log k2o + ρ*?* + δEs (i). log k2 = log k2o + ρ*?* + ψν (ii)
Effects of α Substitution on the Carbonyl Stretching Frequencies of Phenyl Carboxylates
Almeida, Maria Ines de,Amaral, Antonia T. do,Amaral, Luciano do
, p. 1567 - 1571 (2007/10/02)
The infrared carbonyl stretching frequencies for several esters of the general formula R1R2R3C-COOPh were determined in carbon tetrachloride.The ?* and Es Taft parameters as well as the νCharton parameters for the same esters were determined.The carbonyl stretching frequencies are well correlated by a dual substituent parameter treatment: νC=O = νC=O0 + ρ*?* + δES or νC=O = νC=O0 + ρ*?* + ΨνCharton.In both cases the steric parameter is much larger than the polar parameter, suggesting that the effect of the substituents on the carbonyl stretching frequencies is of a steric nature, although a small contribution of the polar effect is observed.
