Indium-mediated chemoselective deprotection of trichloroethoxycarbonyl and trichloroacetyl groups

Valluri, Muralikrishna; Mineno, Tomoko; Hindupur, Rama Mohan; Avery, Mitchell A.

doi:10.1016/s0040-4039(01)01489-7

Cited by 24 publications

(16 citation statements)

References 12 publications

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“…Applying the reaction conditions from our previous work, 16 deprotection of Troc-protected 4-aminobenzonitrile gave poor results even after 5 h of reflux, using 2 equiv of indium (Table 1, entry 1). When the amount of indium was increased to 5 equiv, the reaction proceeded to afford 84% of the desired 4-aminobenzonitrile ( Having improved the deprotection conditions, various aromatic and aliphatic carbamates were prepared by known methods 17 and subjected to the above deprotection conditions.…”

Section: Methodsmentioning

confidence: 96%

“…15 We have recently reported that deprotection of Troc-and trichloroacetyl-protected alcohols can be carried out chemoselectively with indium metal under mild conditions. 16 In an ongoing effort to develop indium-mediated chemistry, we have found that carbamates can also be cleaved chemoselectively under mild conditions, into the corresponding amines using indium metal. Herein, we wish to report the details of our studies on the release of amines from their trichloroethyl carbamates (Scheme).…”

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confidence: 99%

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A Mild Deprotection of Trichloroethyl Carbamates Using Indium Metal

Mineno¹,

Choi²,

Avery³

2002

Synlett

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Section: Methodsmentioning

confidence: 96%

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confidence: 99%

A Mild Deprotection of Trichloroethyl Carbamates Using Indium Metal

Mineno¹,

Choi²,

Avery³

2002

Synlett

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“…In recent years, we have studied the usage of trivalent indium reagents, 22,23) as well as indium metal-based reagents, [24][25][26][27] and reported the catalytic application of indium(III) triflate (In(OTf) 3 ) in the one-step chemical transformations. As part of our ongoing investigations, herein we wish to report the details of our study on the efficient oxidative methyl esterification of aldehydes using In(OTf) 3 .…”

Section: )mentioning

confidence: 99%

The Effect of Indium(III) Triflate in Oxone-Mediated Oxidative Methyl Esterification of Aldehydes

Mineno

Sakai

Ubukata

et al. 2013

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…[22][23][24][25] The authors have recently developed a practical approach to tetrahydropyranylation and depyranylation of various alcohols using indium(III) triflate.…”

Section: Notesmentioning

confidence: 99%

“…[22][23][24][25] The authors have recently developed a practical approach to tetrahydropyranylation and depyranylation of various alcohols using indium(III) triflate. 26) It is worth noting that with the same catalyst, the reactions proceed in directions of both protection and deprotection.…”

Section: Notesmentioning

confidence: 99%

One-Step Transformation of Tetrahydropyranyl Ethers Using Indium(III) Triflate as the Catalyst

Mineno

Nikaido

Kansui

2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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NotesTetrahydropyranyl (THP) group is a well-utilized moiety, mainly as a tool to protect alcohol units due to its feasibility of installation and low cost. Stirring the free alcohols with 3,4-dihydro-2H-pyran (DHP) under acidic conditions can easily produce THP-protected alcohols.1-8) Also, THP-protected alcohols are generally stable under a wide range of reaction conditions and reagents, such as metal hydrides, alkyllithiums, Grignard reagents, and catalytic hydrogenation. O, 19,20) and CuSO 4 · 5H 2 O, 21) has also been reported.Previously, we have reported a couple of convenient reaction methods using indium or indium-related reagents. [22][23][24][25] The authors have recently developed a practical approach to tetrahydropyranylation and depyranylation of various alcohols using indium(III) triflate.26) It is worth noting that with the same catalyst, the reactions proceed in directions of both protection and deprotection. In the presence of a catalytic amount of indium(III) triflate, protection of alcohols is carried out using CH 2 Cl 2 as the solvent, whereas deprotection uses MeOH/H 2 O as the solvent. Kamal et al. also reported that tetrahydropyranylation can be controlled using catalytic aluminum(III) triflate. 27) Another report has shown the cleavage of THP ethers using titanium(III) triflate in good yields.28) According to our earlier experiments, indium(III) triflate was revealed to be an efficient catalyst for the transformation of THP ethers into their corresponding acetates. In further intensive work, we have developed a useful transforming reaction of THP ethers using various anhydride moieties with indium(III) triflate as the catalyst. Herein, we report the details of this one-step transformation. Results and DiscussionTHP-protected benzyl alcohol and N-(2-hydroxyethyl)-phthalimide were used as the starting materials. First, the suitability of the catalysts was examined by reactions with acetic anhydride (Chart 1). In both cases, the reaction proceeded and produced excellent yields in a shorter time when indium(III) triflate was employed as the catalyst (Table 1, entries 1 and 3), as compared with indium(III) chloride (Table 1, entries 2 and 4). Giving the satisfactory results with indium(III) triflate, we then expanded our investigation to the other types of anhydrides. The reactions were carried out with THP-protected benzyl alcohol, N-(2-hydroxyethyl)phthalimide, and a wide range of anhydrides (Chart 2).As expected, the reactions with another aliphatic anhydride of isobutyric anhydride generated similar satisfactory results (Table 2, entries 1 and 7). In the case of benzoic anhydride, the reaction required an extended period of time, although acceptable results were obtained (Table 2, entries 2 and 8). With the exception of entry 5, these conditions were then applied to the cyclic anhydrides, and the reactions produced entirely poor yields. These results were presumably due to the low reaction temperature. When reactions were resumed at reflux using THF as the solvent, good to excellent out...

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Indium-mediated chemoselective deprotection of trichloroethoxycarbonyl and trichloroacetyl groups

Cited by 24 publications

References 12 publications

A Mild Deprotection of Trichloroethyl Carbamates Using Indium Metal

A Mild Deprotection of Trichloroethyl Carbamates Using Indium Metal

The Effect of Indium(III) Triflate in Oxone-Mediated Oxidative Methyl Esterification of Aldehydes

One-Step Transformation of Tetrahydropyranyl Ethers Using Indium(III) Triflate as the Catalyst

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