Stereoselective and Competitive [1,2]‐ and [2,3]‐Wittig Rearrangements of Allyl Heteroarylalkyl Ethers

Capriati, Vito; Florio, Saverio; Ingrosso, Giovanni; Granito, Catia; Troisi, Luigino

doi:10.1002/1099-0690(20022)2002:3<478::aid-ejoc478>3.0.co;2-#

Cited by 30 publications

(19 citation statements)

References 46 publications

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“…An analogous rearrangement for allyl (heteroaryl)alkyl ethers has recently been described [14] and extensively investigated for various substrates. [16] In contrast, substrates 9a, 10a, 13a and 14a underwent the [1,2]-Wittig rearrangement to give the propargylic alcohols as the sole products.…”

Section: Resultsmentioning

confidence: 99%

“…were deprotonated with nBuLi in the presence of iodomethane. Compound 2a exclusively afforded the methylation product 5a (95% yield), while 10a gave the coupling product 10d (30% yield) together with the [1,2]-rearranged product 10b, thus confirming that the occurrence of the [2,3]-or the [1,2]-Wittig rearrangement is governed by the generation of the carbanion at the α-or at the αЈ-carbon atom, respectively [14] (Scheme 3).…”

Section: Resultsmentioning

confidence: 99%

“…72Ϫ73°C (n-hexane). 1 17.1, 57.3, 76.3, 79.6, 84.2, 113.9, 122.0, 127.2, 128.1, 128.4, 128.5, 128.6, 131.8, 139.0, 152.7, 171.2 General Procedure for the Preparation of (Heteroaryl)alkyl Carbinols and Chlorides: (Benzothiazol-2-yl)methanol [21] used for the preparation of ethers 1a and 2a, (1-benzothiazol-2-yl)ethanol [21] used for ethers 4a and 5a, 1-(4-methylthiazol-2-yl)ethanol [14] used for 6a and 9a, and (2-chloromethyl)benzothiazole [21] used for ether 3a were prepared as reported. (4-Methylthiazol-2-yl)phenylmethanol, needed for the preparation of the substrates 7a and 8a, was prepared by direct deprotonation of 4-methylthiazole (5 mmol) in 50 mL of THF at Ϫ78°C, by dropwise addition, under N 2 , first of a solution of nBuLi in hexanes (2.5 , 2.4 mL, 6.0 mmol) and then of a solution of benzaldehyde (6 mmol) in THF (3 mL).…”

Section: -[1-(3-phenylprop-2-ynyloxy)ethyl]benzothiazole (4a)mentioning

confidence: 99%

“…( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002) tereoselectivity and good enantiomeric enrichment. [14] Encouraged by these findings, we next turned our attention to the behaviour of (heteroaryl)alkyl propargyl ethers with strong bases. In this paper we report a stereoselective preparation of propargylic and allenic alcohols, based on [1,2]and [2,3]-Wittig rearrangements of (heteroaryl)alkyl propargyl ethers.…”

Section: Introductionmentioning

confidence: 99%

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Wittig Rearrangements of (Heteroaryl)alkyl Propargyl Ethers − Synthesis of Allenic and Propargylic Alcohols

et al. 2002

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(Heteroaryl)alkyl propargyl ethers have been synthesized and treated with nBuLi in THF at −78 °C. The resulting α‐ or α′‐lithio derivatives could be trapped with iodomethane, affording the corresponding α‐ or α′‐methylated products. Treatment in the absence of an external electrophile resulted either in allenic alcohols or in propargylic alcohols, or in mixtures of both compounds, probably arising from competing [1,2]‐ and [2,3]‐Wittig rearrangements, in varying ratios. A high anti diastereoselectivity was observed in the propargylic alcohols produced. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: -[1-(3-phenylprop-2-ynyloxy)ethyl]benzothiazole (4a)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Wittig Rearrangements of (Heteroaryl)alkyl Propargyl Ethers − Synthesis of Allenic and Propargylic Alcohols

et al. 2002

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“…4 We have also reported that deprotonated allyl heteroarylalkyl ethers afford allylic and homoallylic alcohols. 5 Such…”

Section: Introductionmentioning

confidence: 99%

Regio- and stereo-selective coupling reactions of heteroarylalkyl propargyl ethers with electrophiles

Florio¹,

Granito²,

Ingrosso³

et al. 2003

Arkivoc

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Treatment of heteroarylalkyl propargyl ethers with n-BuLi affords relatively stable α− and α'-carbanions. Deprotonation performed in the presence of electrophiles leads to heteroarylsubstituted propargylic ethers and hydroxyalkylpropargylic ethers, containing new stereogenic centers. When the same reactions were carried out in the presence of an external chiral ligand, fairly good asymmetric induction was observed.

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Asymmetric deprotonation with alkyllithium‐(–)‐sparteine

Hoppe

Christoph

2004

The Chemistry of Organolithium Compounds

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Stereoselective and Competitive [1,2]‐ and [2,3]‐Wittig Rearrangements of Allyl Heteroarylalkyl Ethers

Cited by 30 publications

References 46 publications

Wittig Rearrangements of (Heteroaryl)alkyl Propargyl Ethers − Synthesis of Allenic and Propargylic Alcohols

Wittig Rearrangements of (Heteroaryl)alkyl Propargyl Ethers − Synthesis of Allenic and Propargylic Alcohols

Regio- and stereo-selective coupling reactions of heteroarylalkyl propargyl ethers with electrophiles

Asymmetric deprotonation with alkyllithium‐(–)‐sparteine

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