Synthesis of (1R)-[1-D]-.alpha.-fenchocamphoronequinone

Kokke, W. C. M. C.; VARKEVISSER, F. A.

doi:10.1021/jo00925a011

Cited by 21 publications

(7 citation statements)

References 3 publications

(4 reference statements)

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“…10 Chiral imidazolium-based ionic liquids, 11 (+)-10-Chlorocamphor 3 has previously been obtained from "oxy-camphene", 17 by the oxidation of 10-chloroisoborneol, 18 by the reduction of 8-bromo-3,10-dichlorocamphor using zinc in acetic acid, 19 by triflic anhydride-promoted Wagner-Meerwein rearrangement of (+)-camphor 20 and by prolonged reaction of (+)-10-bromocamphor 4 with LiCl in DMF. 21 Although the facile and direct route to (+)-10-chlorocamphor 3 from (+)-camphor-10-sulfonyl chloride 9 via the method described above makes this a more readily accessible chiral synthon, more efficient routes exist for the preparation of (+)-10-bromocamphor 4 and (−)-10-iodocamphor 5 which can both be accessed from (+)-camphor in 3-steps via the above-mentioned Wagner-Meerwein rearrangement 20 or, in the case of (+)-10-bromocamphor 4, by thermolysis of (+)-camphor-10-sulfonyl bromide 8. 22 A convenient synthesis of (−)-10-iodocamphor 5 directly from commercially available (+)-camphor-10-sulfonic acid via reduction with I 2 /PPh 3 has been previously reported, 23 although to the best of our knowledge this methodology has not been previously applied to the synthesis of either 3 or 4.…”

Section: Methodsmentioning

confidence: 99%

“…The first product to elute was (+)-10-chlorocamphor 3 as a white solid (0.65 g, 81 %); Mp 129 o C (ether/hexane); Lit. 21 1455, 1414, 1375, 1301, 1219, 1168, 1101, 1053, 1006, 982, 934, 853, 762, 716, 639 cm -1 . 1 H NMR (CDCl 3 ): 0.99 (s, 3H, 7-CH 3 ), 1.13 (s,3H, 1453,1412,1375,1301,1219,1168,1102,1062,1006,982,944,859,765,711,645 …”

Section: Methods B: From Sulfonic Acid 12mentioning

confidence: 99%

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Unexpected formation of 10-iodo- and 10-chlorocamphor under halosulfonylation conditions, and convenient routes to 10-chloro- and 10-bromocamphor

Lewis

Egron

Grayson

2009

Tetrahedron: Asymmetry

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Abstract-Generation of camphor-10-sulfonyl iodide in situ under halosulfonylation conditions or exposure of camphor-10-sulfonyl chloride to copper (II) chloride under Asscher-Vofsi conditions unexpectedly leads to the formation of 10-iodocamphor or 10-chlorocamphor respectively. Additionally, convenient syntheses of 10-bromocamphor and 10-chlorocamphor have been achieved by extension of previously reported methodology.

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Section: Methodsmentioning

confidence: 99%

Section: Methods B: From Sulfonic Acid 12mentioning

confidence: 99%

Unexpected formation of 10-iodo- and 10-chlorocamphor under halosulfonylation conditions, and convenient routes to 10-chloro- and 10-bromocamphor

Lewis

Egron

Grayson

2009

Tetrahedron: Asymmetry

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“…Both the (+)-enantiomer, (I), of known absolute stereochemistry (m.p. ca 508 K; Kokke & Varkevisser, 1974), prepared as described by Bartlett & Knox (1973), and the racemate, (II) (m.p. ca 511 K), prepared by the same method, were crystallized from ethanol-water.…”

Section: Methodsmentioning

confidence: 99%

(+)- and (±)-ketopinic acid: hydrogen-bonding patterns in a β-keto acid in its enantiomeric and racemic forms and enantiomeric disordering in the racemate

et al. 1999

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“…Compound II was not formed when ketone I was added to the system solid NH 4 Cl-LDA or solid NH 4 Cl-solid LiOH-i-Pr 2 NH in THF, which was prepared preliminarily under argon. The structure of ketone II was confirmed by the spectral data and chemical reactions, specifically by the transformation of II into ester III and acid IV [8,9]. Chlorovinyl ketone II attracts interest primarily as a new chiral initial compound in target-oriented syntheses.…”

mentioning

confidence: 89%

“…Acid IV was synthesized by alkaline hydrolysis of ester III under standard conditions. mp 225-228°C (from water); published data: mp 227-229°C [8].…”

Section: Methyl 77-dimethyl-2-oxobicyclo[221]heptane-1-carboxylatementioning

confidence: 99%

Synthesis of (+)-(1S,4R)-1-(1-chlorovinyl)-7,7-dimethyl-bicyclo[2.2.1]heptan-2-one

et al. 2004

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SHORT COMMUNICATIONS7,7-Dimethyl-1-vinylbicyclo[2.2.1]heptan-2-one (I) which is readily accessible from d-camphorsulfonic acid [1] is extensively used in the synthesis of taxoids [2,3] and their precursors [4]. No specific chemical properties of keto olefin I have been noted; for example, by the action of deprotonating agents it gives rise to expected enolates which are involved in reactions typical of such derivatives [5,6]. While trying to effect Michael reaction of methyl propynoate with the enolate generated from ketone I by the action of lithium diisopropylamide (LDA), we have found that the process takes an unexpected path. After treatment of the reaction mixture with an aqueous solution of NH 4 Cl and purification of the crude product on silica gel, we isolated (+)-(1S,4R)-1-(1-chlorovinyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-one (II) in a moderate yield. Clearly, methyl propynoate does not participate in this transformation. Therefore, we carried out the reaction under analogous conditions but without addition of methyl propynoate. Compound I was treated with 3 equiv of LDA in THF at -78 to 20°C over a period of 1 h; the mixture was then kept for 12 h at 20°C and was treated with an aqueous solution of ammonium chloride. As a result, we isolated chlorinecontaining ketone II in a good yield. When water was used instead of aqueous NH 4 Cl for quenching of the reaction mixture, initial ketone I was recovered from the mixture. The yield of II did not change on replacement of LDA by Et 2 NLi; no reaction occurred with NaN(Pr-i) 2 . Compound II was not formed when ketone I was added to the system solid NH 4 Cl-LDA or solid NH 4 Cl-solid LiOH-i-Pr 2 NH in THF, which was prepared preliminarily under argon. The structure of ketone II was confirmed by the spectral data and chemical reactions, specifically by the transformation of II into ester III and acid IV [8,9]. Chlorovinyl ketone II attracts interest primarily as a new chiral initial compound in target-oriented syntheses. Presumably, the mechanism of formation of compound II involves generation of hypochlorite-like chlorinating intermediates during treatment of the reaction mixture with aqueous ammonium chloride. (+)-(1S,4R)-1-(1-Chlorovinyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-one (II).To a solution of 191 mg (1.89 mmol) of diisopropylamine in 5 ml of tetrahydrofuran we added at 0°C under argon 0.59 ml (1.83 mmol) of a 3.1 N solution of butyllithium in hexane. The mixture was stirred for 15 min and cooled to -78°C, and a solution of 100 mg (0.61 mmol) of olefin I in 5 ml of THF was added dropwise to the resulting solution of lithium diisopropylamide. The mixture was stirred for 30 min, allowed to warm up to 20°C, kept for 12 h at that temperature, and treated with 5 ml of a saturated aqueous solution of ammonium chloride. The solvent was distilled off, and the aqueous phase was extracted with ethyl acetate (3 × 10 ml). The extract was dried over MgSO 4 , the solvent O I (1) LiN(Pr-i) 2 , 3 equiv (2) Aq. NH 4 Cl 71% O II O 3 , MeOH Cl MeOCO O III 65% HOCO O IV 9...

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Synthesis of (1R)-[1-D]-.alpha.-fenchocamphoronequinone

Abstract: leads to 30-40% yields of 1 (m = n = 5) and 1 (m = n = 7 ) .

Cited by 21 publications

References 3 publications

Unexpected formation of 10-iodo- and 10-chlorocamphor under halosulfonylation conditions, and convenient routes to 10-chloro- and 10-bromocamphor

Unexpected formation of 10-iodo- and 10-chlorocamphor under halosulfonylation conditions, and convenient routes to 10-chloro- and 10-bromocamphor

(+)- and (±)-ketopinic acid: hydrogen-bonding patterns in a β-keto acid in its enantiomeric and racemic forms and enantiomeric disordering in the racemate

Synthesis of (+)-(1S,4R)-1-(1-chlorovinyl)-7,7-dimethyl-bicyclo[2.2.1]heptan-2-one

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