Tosylhydrazones.  V. Reaction of Tosylhydrazones with Alkyllithium Reagents.  A New Olefin Synthesis.

Shapiro, Robert H.; Heath, Marsha J.

doi:10.1021/ja00998a601

Cited by 254 publications

(109 citation statements)

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“…Application of the Shapiro reaction 29) for construction of a C-C double bond from ketone (11) was examined first. Reaction of 11 with p-toluenesulfonylhydrazine in ethanol in the presence of concentrated hydrochloric acid gave hydrazone (12) in 91% yield.…”

Section: )mentioning

confidence: 99%

Stereoselective Synthesis of C3-C12 Dihydropyran Portion of Antitumor Laulimalide Using Copper-Catalyzed Oxonium Ylide Formation-[2,3] Shift

Yakura

Muramatsu

Uenishi

2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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Tetrahydropyran and dihydropyran rings are structural components of a large number of natural products.1,2) Therefore, considerable attention has recently been directed toward their stereoselective synthesis. [3][4][5][6][7][8] The microtubule-stabilizing agent (Ϫ)-laulimalide, 9-18) also known as fijianolide B, which was isolated from several sponges (Cacospongia mycofijiensis,19) Hyattella sp., 20) Fasciospongia rimosa 21) ), contains 2,6-trans disubstituted 5,6-dihydro-2H-pyran as its C5-C9 portion. Stereoselective construction of thermodynamically less stable 2,6-trans substituted pyrans is one of most important subjects in synthesis of this attractive antitumor agent and its analogues.Metal catalyzed carbenoid reactions 22,23) have become a powerful tool for the synthesis of functionalized cyclic compounds including oxacycles. In 1994, Clark and co-workers reported that a copper-catalyzed reaction of 5-allyoxy-1-diazo-2-hexanone predominantly gave 2,6-trans-2-allyl-6-methy-3-dihydropyranone in good yield.24) This result stimulated us to investigate the metal catalyzed stereoselective synthesis of 2,6-trans disubstituted 3-pyranone (2) from adiazoketone (3) as a feasible method for synthesis of the C5-C9 portion of laulimalide and its analogues because 3 would be converted easily into the key intermediate (1) of the Mulzer's laulimalide synthesis, 11,25) as outlined in Chart 1. Herein, we describe the synthesis of 2 in high yield with excellent stereoselectivity by the copper-catalyzed oxonium ylide formation-[2,3] shift of 3 and conversion of 2 into 1 and its derivatives.a-Diazoketone (3) was prepared readily from the known alcohol (4) 11) as shown in Chart 2. Homoallylic alcohol (4) was converted to diol by hydroboration-oxidation process with borane-tetrahydrofuran (THF) complex and subsequent treatment with hydrogen peroxide and sodium hydroxide. Then the resulting primary hydroxyl group was protected as a tert-butyldimethylsilyl (TBDMS) ether to give the secondary alcohol (5) in high yield. O-Allylation of 5 was troublesome. Under usual allylation conditions, such as reaction with sodium hydride (NaH) and allyl bromide in THF, no reaction occurred. Several examinations revealed that treatment of 5 with NaH and allyl iodide in the presence of 15-crown-5 in THF at room temperature afforded allyl ether (6) in 96% yield. Deprotection of TBDMS group with tetrabutylammonium fluoride (TBAF), followed by two stepoxidation with Dess-Martin periodinane and oxone in dimethylformamide (DMF) 26) gave carboxylic acid (7) in 80% overall yield. Conversion of 7 into a-diazoketone (3) was achieved by the usual procedure, 27) formation of mixed acid anhydride with ethyl chloroformate and treatment with diazomethane, thereby providing 3 in 85% yield in two steps.With a-diazoketone (3) in hand, we turned our attention to cyclization of 3 by the metal catalyzed reaction (Eq. 1).(1)Formation of 2,6-disubstituted 3-pyranone using oxonium ylide formation-[2,3] shift of a-diazoketone has already been examined. Clark and co-worke...

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Section: )mentioning

confidence: 99%

Stereoselective Synthesis of C3-C12 Dihydropyran Portion of Antitumor Laulimalide Using Copper-Catalyzed Oxonium Ylide Formation-[2,3] Shift

Yakura

Muramatsu

Uenishi

2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…Moreover, to accomplish the Bamford-Stevens reaction it is essential a good leaving group, like the tosyl group, is attached to the hydrazone. [8,9,19] Although the Shapiro reduction also requires a good leaving group attached to the hydrazone, the special acidic properties of this kind of compounds allow an oxygen-assisted variant of this mechanism to be considered as a possible alternative. The acidity measurements in DMSO reported by Bordwell et al for the N À H groups of 2-pyridone 30 (pK a = 17.0) [20] and of some hydrazones (acetophenone phenylhydrazone 31, pK a = 21.6, benzaldehyde phenylhydrazone 32, pK a = 21.1 and 9-fluorenone phenylhydrazone 33, pK a = 14.9) [21] are evidence for regarding that the endocyclic NÀH of the hydrazone-tautomer derivatives presented in this work [22] must have similar acidic properties, if not higher, than the hydrazone amine group (Scheme 12).…”

Section: Mechanistic Aspects Of the Novel Reactionmentioning

confidence: 99%

Reduction of Different Electron‐Poor N‐Heteroarylhydrazines in Strong Basic Conditions

Unciti‐Broceta

Infantas

Gallo

et al. 2007

Chemistry A European J

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The first application of the Wolff-Kishner reduction methodology to electron-poor heteroaromatic compounds is reported. Hydrazino-containing heterocycles with hydrazone-type tautomery have been reduced under basic conditions. This novel chemistry was successfully applied to mono-dehalogenate a number of electron-poor heterocycles in a regioselective manner. According to the experimental results, this reductive process is a base-catalyzed reaction that takes only place in the presence of air, probably through an oxygen-assisted mechanism. As consequence of the specific features of this kind of hydrazone/enehydrazine tautomers, the overall outcome of the process is the synthesis of a Shapiro-type reduction product by simply using a milder version of the Huang-Minlon methodology.

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“…Crystallization from ethanol of the first band gave 110.0 mg (83%) of colourless 6,7-dimethyl-10-methoxybenzocyclooctatetraene (16), mp 68.5-70.5"C; ir (melt): 810, 825, and 840, trisubstituted vinyls; uv: 230 sh (13 300 COT 9 from ketone I 7 via the Shapiro reaction (ref. 13) A solution of 1.0153 g (5.1 mmol) of 17, 50 mg (0.26 mmol) of p-toluenesulfonylchloride, and 1.30 g (7.0 mmol) of ptoluenesulfonylhydrazide in 25 mL methanol was stirred at room temperature for 24 h and then cooled to -12°C for 12 h. The precipitate was filtered, washed with cold methanol, and dried in vacuo to give 1.7335 g (93%) of the tosylhydrazone as a white solid, mp 166-168°C dec. A solution of 3 mL (0.48 mmol) of 1.6 M methyllithium in ether was slowly ( I min) titrated into an ice-cooled, stirred sluny of 345.0 mg (0.95 mmol) of the tosylhydrazone in 20 mL of dry ether under argon until the mixture just maintained an orange colour. A second 3-mL aliquot of the methyllithium was added during I min.…”

Section: Gas Phase Thermolysis Of Sb 15mentioning

confidence: 99%

Evidence for a di-π-methane rearrangement in the photoisomerization of 2,3-benzo-7,8-dimethylbicyclo[4.2.0]octa-2,4,7-triene to 6,7-dimethylbenzotricyclo[3.3.0.0^2,8]octa-3,6-diene

Bender¹,

Cassis²,

Dolman³

et al. 1984

Can. J. Chem.

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, 2769 (1984). The direct and sensitized (Michler's ketone) irradiations of 2,3-benzo-7,8-dirnethylbicyc10[4.2.0]octa-2,4,7-triene (7) yield 6,7-dirnethylbenzotricycIo[3.3.0.02~X]octa-3,6-diene (3, @ = 0.030 and 0.093, respectively) and naphthalene (@ = 0.10 and 0.16, respectively). Deuterium labelling studies suggest that 3 derives from a Zimrnerrnan di-7-methane rearrangement of 7, and that 1,8-dimethyl-la,2,7,7a-tetrahydro-1,2,7-metheno-l H-cyclopropa

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Tosylhydrazones. V. Reaction of Tosylhydrazones with Alkyllithium Reagents. A New Olefin Synthesis.

Cited by 254 publications

References 1 publication

Stereoselective Synthesis of C3-C12 Dihydropyran Portion of Antitumor Laulimalide Using Copper-Catalyzed Oxonium Ylide Formation-[2,3] Shift

Stereoselective Synthesis of C3-C12 Dihydropyran Portion of Antitumor Laulimalide Using Copper-Catalyzed Oxonium Ylide Formation-[2,3] Shift

Reduction of Different Electron‐Poor N‐Heteroarylhydrazines in Strong Basic Conditions

Evidence for a di-π-methane rearrangement in the photoisomerization of 2,3-benzo-7,8-dimethylbicyclo[4.2.0]octa-2,4,7-triene to 6,7-dimethylbenzotricyclo[3.3.0.0^2,8]octa-3,6-diene

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Tosylhydrazones. V. Reaction of Tosylhydrazones with Alkyllithium Reagents. A New Olefin Synthesis.

Cited by 254 publications

References 1 publication

Stereoselective Synthesis of C3-C12 Dihydropyran Portion of Antitumor Laulimalide Using Copper-Catalyzed Oxonium Ylide Formation-[2,3] Shift

Stereoselective Synthesis of C3-C12 Dihydropyran Portion of Antitumor Laulimalide Using Copper-Catalyzed Oxonium Ylide Formation-[2,3] Shift

Reduction of Different Electron‐Poor N‐Heteroarylhydrazines in Strong Basic Conditions

Evidence for a di-π-methane rearrangement in the photoisomerization of 2,3-benzo-7,8-dimethylbicyclo[4.2.0]octa-2,4,7-triene to 6,7-dimethylbenzotricyclo[3.3.0.02,8]octa-3,6-diene

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Evidence for a di-π-methane rearrangement in the photoisomerization of 2,3-benzo-7,8-dimethylbicyclo[4.2.0]octa-2,4,7-triene to 6,7-dimethylbenzotricyclo[3.3.0.0^2,8]octa-3,6-diene