- PROCESSES FOR PREPARING 2-ISOPROPENYL-5-METHYL-4-HEXENOIC ACID, 2-ISOPROPENYL-5-METHYL-4-HEXEN-1-OL, AND A CARBOXYLATE ESTER THEREOF
-
The present invention provides a process for preparing 2-isopropenyl-5-methyl-4-hexenoic acid of the following formula (4), comprising steps of: subjecting a Grignard reagent of the following general formula (1), wherein R1 represents a linear, branched, or aromatic monovalent hydrocarbon group having 1 to 8 carbon atoms, and X represents a chlorine atom, a bromine atom, or an iodine atom, and 1,1,1,3,3,3-hexamethyldisilazane to a deprotonation reaction to form a 1,1,1,3,3,3-hexamethyldisilazane derivative; and subjecting 2-methyl-3-buten-2-yl 3-methyl-2-butenoate of the following formula (3) to a rearrangement reaction in the presence of the 1, 1, 1,3,3,3-hexamethyldisilazane derivative to form 2-isopropenyl-5-methyl-4-hexenoic acid (4).
- -
-
-
- Fungal mediated kinetic resolution of racemic acetates to (R)-alcohols using Fusarium proliferatum
-
Fungal mediated kinetic resolution of seven acyclic/aromatic acetates was achieved using Fusarium proliferatum to furnish (R)-alcohols in high enantiomeric excess (>95%). The kinetic resolution was established as one-pot two-step de-esterification/oxidation biocatalytic process. Further, the preparative scale synthesis of (R)-(+)-1-phenylethanol was accomplished through de-esterification/oxidation of (±)-1-phenylethyl acetate using the whole cell of F. proliferatum NCIM 1105.
- Jadhav, Dipesh D.,Patil, Harshal S.,Chaya, Patil S.,Thulasiram, Hirekodathakallu V.
-
p. 4563 - 4567
(2016/09/23)
-
- Biomimetic total synthesis of (±)-doitunggarcinone A and (+)-garcibracteatone
-
A full account of our oxidative radical cyclization approach to the synthesis of garcibracteatone and doitunggarcinone A is presented. This includes the first enantioselective synthesis of garcibracteatone, which allowed the absolute configuration of the natural compound to be determined. The first synthesis of doitunggarcinone A is also described, which confirms our reassignment of the relative configuration of this molecule. Novel syntheses of monoterpene fragments used to construct the target molecules are also reported.
- Pepper, Henry P.,Tulip, Stephen J.,Nakano, Yuji,George, Jonathan H.
-
p. 2564 - 2573
(2014/04/17)
-
- Chrysanthemyl diphosphate synthase operates in planta as a bifunctional enzyme with chrysanthemol synthase activity
-
Chrysanthemyl diphosphate synthase (CDS) is the first path-way-specific enzyme in the biosynthesis of pyrethrins, the most widely used plant-derived pesticide. CDS catalyzes c1′-2-3 cyclopropanation reactions of two molecules of dimethylallyl diphosphate (DMAPP) to yield chrysanthemyl diphosphate (CPP). Three proteins are known to catalyze this cyclopropanation reaction of terpene precursors. Two of them, phytoene and squalene synthase, are bifunctional enzymes with both prenyltransferase and terpene synthase activity. CDS, the other member, has been reported to perform only the prenyltransferase step. Here we show that the NDXXD catalytic motif of CDS, under the lower substrate conditions prevalent in plants, also catalyzes the next step, converting CPP into chrysanthemol by hydrolyzing the diphosphate moiety. The enzymatic hydrolysis reaction followed conventional Michaelis-Menten kinetics, with a Km value for CPP of 196 μM. For the chrysanthemol synthase activity, DMAPP competed with CPP as substrate. The DMAPP concentration required for half-maximal activity to produce chrysanthemol was ～100 μM, and significant substrate inhibition was observed at elevated DMAPP concentrations. The N-terminal peptide of CDS was identified as a plastid-targeting peptide. Transgenic tobacco plants overexpressing CDS emitted chrysanthemol at a rate of 0.12-0.16 μg h-1 g-1 fresh weight. We propose that CDS should be renamed a chrysanthemol synthase utilizing DMAPP as substrate.
- Yang, Ting,Gao, Liping,Hu, Hao,Stoopen, Geert,Wang, Caiyun,Jongsma, Maarten A.
-
p. 36325 - 36335
(2015/02/19)
-
- A new synthesis of lavandulol via indium/palladium-mediated umpolung of vinyloxirane
-
A short synthesis of lavandulol is achieved by the In/Pd-mediated reaction of isopropenyloxirane with 3-methylbut-2-enal.
- Araki, Shuki,Kambe, Shinya,Kameda, Keiko,Hirashita, Tsunehisa
-
p. 751 - 754
(2007/10/03)
-
- Synthesis of 6-(poly)prenyl-substituted polyprenols and their phosphates
-
The 6-(poly)prenyl-substituted polyprenols 7, 9, 11, and 13 were synthesized: (1) 7 from 2-geranyl-farnesal and methyl 4-bromo-3-methyl-2- butenoate, (2) 9 from 2-prenyl-geranyl bromide and ethyl acetoacetate, via ketone 29, (3) 11 from ethyl acetoacetate, geranyl bromide, and (E)-1-t- butyldiphenylsiloxy-5-iodo-3-methyl-2-pentene, via β-keto ester 35, and (4) 13 from geraniol by acid catalyzed condensation. These highly branched polyprenols 7, 9, 11, and 13 were transformed into the corresponding disodium phosphates 8, 10, 12, and 14, respectively.
- Nagano, Hajime,Nakanishi, Eiyu,Takajo, Saho,Sakuma, Masako,Kudo, Kaori
-
p. 2591 - 2608
(2007/10/03)
-
- A synthesis of (±)-lavandulol using a silyl-to-hydroxy conversion in the presence of 1,1-disubstituted and trisubstituted double bonds
-
Silylcuprates and silylzincates react with α,β-unsaturated aldehydes, esters, ketones and amides 19 unsubstituted at the β-position in higher yield if trimethylsilyl chloride is present. Applying this method, conjugate addition of the silylcuprate 26 derived from (Z)-chloro(2-methylbut-2-enyl)diphenylsilane 24, itself prepared by an improved route, to 3-methylene-6-methylhept-5-en-2-one 25 gave 3-[(Z)-2-methylbut-2-enyl(diphenyl)silyl]methyl-6-methylhept-5-en-2-one 27. A Wittig reaction gave 3-[(Z)-2-methylbut-2-enyl(diphenyl)silyl]methyl-2,6-dimethylhepta-1,5-diene 28 and silyl-to-hydroxy conversion gave lavandulol 1, even in the presence of the 1,1-disubstituted and trisubstituted double bonds. The hydroxy group of the 3-hydroxysilane, 2,6-dimethyl-3-{[(Z)-2-methylbut-2-enyl]diphenylsilyl}methylhept-5-en-2-ol 30, activated the allylsilane group towards protodesilylation. Chloro(diphenyl)methallylsilane 35 is easier to make than the chloride 24, and should be an alternative allylsilane that can make a lithium and hence a cuprate reagent like 26.
- Fleming, Ian,Lee, Duckhee
-
p. 2701 - 2709
(2007/10/03)
-
- Conjugate addition of silyl groups to β-unsubstituted enones, and Si-to-OH conversion: A synthesis of (±)-lavandulol
-
TMS chloride raises the yield in the conjugate addition of silylcuprates and zincates to β-unsubstituted enones, and Si-to-OH conversion is possible using the 2-methylbut-2-enyl(diphenyl)silyl group in the presence of highly nucleophilic alkenes. Both reactions are used in a synthesis of lavandulol.
- Fleming, Ian,Lee, Duckhee
-
p. 6929 - 6930
(2007/10/03)
-
- Enantio- and diastereoselective protonation of photodienols: Total synthesis of (R)-(-)-lavandulol
-
The total synthesis of (R)-(-)-lavandulol 1 has been achieved by asymmetric protonation of photodienols obtained from the irradiation of prochiral α,β-unsaturated esters. The photodeconjugation of ethyl 5-methyl-2-(1'-methylethylidene)-4-hexenoate (3a), carried out in the presence of catalytic amounts of a β-amino alcohol prepared from (±)-camphor, gives the β,γ-unsaturated isomer 2a in good yields but with moderate enantioselectivities (40% ee). In contrast, irradiation of the corresponding ester 3b, bearing the 1,2:5,6-di-O-isopropylidene-D-glucose group as a chiral alkoxy moiety, affords the deconjugated product 2b in high de (> 95%). Simple reduction of the ester function with LiAlH4 gives (R)-(-)-lavandulol (1) without loss of optical purity.
- Piva
-
p. 7879 - 7883
(2007/10/03)
-
- A New Type of Catalysis by Copper(I) Salts in the Barbier-type Aldehyde Allylation with Tin(II) Chloride. Short Syntheses of (+/-)-Lavandulol and its γ, δ-Dihydro Derivative
-
Copper(I) halides and cyanide catalyse the Barbier-type aldehyde allylation with allylic bromides, chlorides or sulfonates and tin(II) chloride enabling the reaction to take place under very mild conditions with high efficiency.
- Imai, Toshiro,Nishida, Shinya
-
p. 277 - 278
(2007/10/02)
-
- Oxalic acid catalyzed isoprenic coupling: a simple experimental procedure.
-
Oxalic acid, which is considered as a mild acid, allows a smooth dehydration- without polymerisation- of 2-methylbut-3-en-2-ol 1 into isoprene with around 46percent yield.The remander of the reaction mixture featuring a nice fragance, consists of a mixture of 25 identified products composed of a set of cyclic and non cyclic ethers, and of monoterpenes.Fourteen products could be isolated by preparative vapor phase chromattography and identified with authentic products by 1H and 13C NMR.The formation of the observed products can be rationalized on the basis of currently admitted reaction mechanisms. Key words: isoprene / isoprene coupling / monoterpenic alcohols
- Bertrand, M.,Waegell, B.,Zahra, J. P.
-
p. 904 - 910
(2007/10/02)
-
- Highly efficient terpenoid pheromone syntheses via regio-and stereocontrolled processing of allyllithiums generated by reductive lithiation of allyl phenyl thioethers
-
Previous work had shown that reducuve lithiation of allyl phenyl thioethers, followed by transmetallation, produces allylmetallics which react selectively with carbonyl compounds at the most or least substituted terminus; the latter results in mainly cis olefin. This technology allows extremely efficient syntheses of racemic versions of lavandulol (two-pot, 70% yield), the Comstock mealy bug pheromone (one-pot, 45% yield) and the California red scale pheromone (4-steps, 23% yield).
- McCullough, Dennis W.,Bhupathy,Piccolino, Elvio,Cohen, Theodore
-
p. 9727 - 9736
(2007/10/02)
-
- REGIOSELECTIVE SYNTHESIS OF α-ALKYLATED-β,γ-ENOATES BY REDUCTION-ALKYLATION WITH CUPRATES-ALKYL HALIDES OF γ-(BENZOTHIAZOLE-2-THIO)-α,β-ENOATES
-
γ-(Benzothiazole-2-thio)-α,β-enoates 3-5 are reductively cleaved by lithium or magnesium cuprates to give enoate anions which are alkylated in situ leading to α-alkylated-β,γ-enoates.The high regioselectivity of the alkylation step is applied to the synthesis of esters of the monoterpenoid lavandulic acid 12.
- Calo, Vincenzo,Lopez, Luigi,Pesce, Giannangelo
-
p. 203 - 205
(2007/10/02)
-
- Selective 1,5-Diene Synthesis. A Radical Approach
-
A new synthetic route to 1,5-dienes is described.Irradiation of a mixture of allyl bromides and allyl sulfides in the presence of hexamethylditin gives the cross-coupled products selectively.
- Yanagisawa, Akira,Noritake, Yoshiyuki,Yamamoto, Hisashi
-
p. 1899 - 1902
(2007/10/02)
-
- Regio- and Stereoselective Synthesis of Allylic and Homoallylic Alcohols by the Reductive Desulfonylation of Allylic Sulfone Derivatives. Application to the Syntheses of (+/-)-Lavandulol and Isolavandulol
-
Regio- and stereoselective desulfonylation of β-tosylhomoallylic alcohols provided a convenient method for the preparation of allylic and homoallylic alcohols. (+/-)-Lavandulol and isolavandulol were synthesized in excellent yields by this method.
- Inomata, Katsuhiko,Igarashi, Susumu,Mohri, Mitsunobu,Yamamoto, Taku,Kinoshita, Hideki,Kotake, Hiroshi
-
p. 707 - 710
(2007/10/02)
-
- Carbon-carbon bond formation employing organoiron reagents. Syntheses of lavandulol and red scale pheromone
-
Some aspects of the chemistry of (η1-allyl)Fp complexes [Fp =η5-C5H5Fe(CO)2] are briefly reviewed, especially the means available for their elaboration. The range of electrophiles which react with (η1-allyl)Fp complexes has been enlarged to include allyl iodides. Two examples of this reaction are given, the first leading to lavandulol 9, the second providing a short synthesis of the red scale pheromone (R,S-15).
- Celebuski,Rosenblum
-
p. 5741 - 5746
(2007/10/02)
-
- METALLATION ET ALKYLATION DES THIOIMIDOESTERS: APPLICATION EN SYNTHESE
-
Alkylation of delocalized anions resulting from metallation of N-phenyl thioimidoesters (precursors of dithioesters and thiolesters) takes place on nitrogen with "saturated" thioimidoesters (alkane thiomidates).On the contrary, unsaturated thiomidoesters (α or β-ethylenic, α-arylated) are regioselectively alkylated on the α carbon atom by alkyl or allylic halides.The possibilities for synthesis offered by successive uses of the reactivities of thioimidoester and dithioester functions (allowing in particular two electrophilic additions on two vicinal carbons) are illustrated by syntheses of terpenic compounds lavandual (and lavandulol) and ar-curcumene.
- Masson, S.,Mothes, V.,Thuillier, A.
-
p. 1573 - 1580
(2007/10/02)
-
- BIOMIMETIC ENTRY TO ACYCLIC TERPENE SYNTHESIS. A NOVEL REARRANGEMENT OF ALLYL ETHER CATALYZED BY ORGANOALUMINUM REAGENTS
-
The intramolecular prenyltransfer reaction is accomplished by the rearrangement of allyl ethers with (2,6-di-tert-butyl-4-methylphenoxy)methylaluminum trifluoromethanesulfonate.The present method provides a simple and highly efficient synthesis of lavandulol.
- Yamamura, Yoshihiro,Umeyama, Kensuke,Maruoka, Keiji,Yamamoto, Hisashi
-
p. 1933 - 1936
(2007/10/02)
-
- Metalated Unsaturated Amides. Regio- and Stereoselective γ-Alkylation
-
The reactions of lithiated and dilithiated unsaturated amides 4, 5, 12, 15, 18, 34, and 36 with a variety of electrophiles have been shown to produce deconjugated, α-alkylated products 6, 7, 13, 16, 19, 35, and 37, respectively, in good to excellent yields (Tables I, II, IV, and VI).Whereas lithiated 4 and dilithiated 5 do not undergo γ-alkylation, the corresponding species of 12 and 15, when converted to their cuprates by using cuprous iodide, afford γ products 4 and 17 with good regio- (67-90percent) and Z stereoselectivity (67-80percent) for E = allyl, prenyl, and geranyl.Differences between the reactions of cuprated, unsaturated amides and unsaturated carboxylic acids with nonallylic alkylating agents are discussed.The reaction of dicuprated N-methylsenecioamide (15) with prenyl bromide leads to a complex mixture of products which have been separated and characterized (Scheme III).The reaction of lithiated N,N-dimethylsenecioamide (18) with aromatic and pyridine aldehydes and some ketones has been shown to provide α (19) or γ (20) products, depending on the conditions of the reaction (Table VI).In this reaction, the reversible formation of the α product 19 and its conversion into the γ product 20 have been demonstrated (Scheme IV).The utility of the α- and γ-alkylated unsaturated amide products is illustrated by the syntheses of the monoterpenoid lavandulol (42) and the amide alkaloid piperlonguminine (43), respectively.
- Majewski, M.,Mpango, G. B.,Thomas, M. T.,Wu, A.,Snieckus, V.
-
p. 2029 - 2045
(2007/10/02)
-
- A BIOMIMETIC SYNTHESIS OF CHRISANTEMOL
-
The factors governing the competition between 1,2- and 1,3-eliminations have been studied and the results obtained have been applied to a biomimetic synthesis of chrysantemol.
- Babin, D.,Fourneron, J. D.,Harwood, L. M.,Julia, M.
-
p. 325 - 332
(2007/10/02)
-
- Synthesis of (+/-)-Lavandulol and its Related Homoallylic Alcohol via Allyl Transfer from Sulphur to Tin
-
(+/-)-Lavandulol and related homoallylic alcohols were prepared by the stannolysis of allylic sulphones and the subsequent hydroxymethylation of the resulting allylic stannanes with trioxan-BF3*OEt2.
- Ueno, Yoshio,Aoki, Seiichi,Okawara, Makoto
-
p. 683 - 684
(2007/10/02)
-
- CONDENSATIONS BIOMIMETIQUES: EDIFICATION DE SQUELETTES TERPENIQUES A PARTIR DE SYNTHONS ISOPRENIQUES
-
The action of perchloric, trifluoroacetic and formic acids on the 1,1-(and 3,3-) dimethylallylic alcohols has been studied.In the presence of formic acid in dichloromethane 2-methyl-3-butene-2-ol (DMVC) has been condensed on the acetate of 3-methyl-3-butene-1-ol (IPA) giving geranylic and lavandulylic type 1,1-adducts.Saponification, dehydration, oxidation and isomerisation of the former type lead to citral.In the same medium, DMVC produces (after saponification) a C10 glycol which upon dehydration produces lavandulol in a convenient way.Geraniol and its acetate have been condensed with low yield on IPA giving farnesylic derivatives.
- Babin, Didier,Fourneron, Jean-Dominique,Julia, Marc
-
p. 588 - 600
(2007/10/02)
-
