On the mechanism and stereochemistry of hydrogen transfer involving photodeoxygenation of sugar esters in hexamethylphosphoric triamide/water

Klausener, Alexander; Beyer, Gerhard; Leismann, Hans; Scharf, Hans‐Dieter; Müller, E.; Runsink, Jan; Görner, Helmut

doi:10.1016/s0040-4020(01)81079-6

Cited by 19 publications

(6 citation statements)

References 42 publications

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“…We first postulated a possible pathway that involved a photoinduced single electron transfer process (PET) upon irradiation of 17 ( i.e ., pathway A, Scheme ). − The resulting ionic diradical intermediate 17 ′ would undergo intramolecular proton abstraction to provide the radical cation of 4 and the corresponding radical anion of the released acid. Subsequent SET within the pair would result in styrene 4 and carboxylic acid 20 .…”

Section: Resultsmentioning

confidence: 99%

“…Another reason for the higher production of elimination than solvolysis may be due to the involvement of pathway D in the photolysis of 17 (Scheme ). Thus, intermediate 17′ can undergo homolysis of the benzylic C–O bond to release carboxylate 22 and produce cationic diradical intermediate 23 . − This open-shell diradical intermediate might convert to closed-shell benzylic cation 21 , since it was estimated that the triplet of intermediate 23 was ∼ 11.2 kcal/mol higher in energy than ground state benzylic cation 21 based on density functional theory (DFT) computation (B3LYP/6-31G(d,p)) . Intermediate 21 would lead to styrene 4 as in pathway B.…”

Section: Resultsmentioning

confidence: 99%

“…The crude product mixture was purified with flash column chromatography (Hex/EA 20:1, R f = 0.3) to provide ester 18 (75.0 mg, 93%) as a colorless oil; 1 H NMR (700 MHz, CDCl 3 ) δ 7.17 (t, J = 8.01 Hz, 1 H), 6.63−6.62 (m, 2 H), 6.60 (d, J = 7.9 Hz, 1 H), 5.82 (s, 1 H), 3.35 (q, J = 7. (19). To the solution of 3-(diethylamino) benzaldehyde (354.0 mg, 2.0 mmol) in 5.0 mL of THF was added t-BuMgCl (1.7 M in THF, 1.5 mL, 2.6 mmol) at 0 °C.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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1-[3-(Diethylamino)phenyl]ethyl (DEAPE): A Photolabile Protecting Group for Hydroxyl and Carboxyl Groups

Ding

Wang

2018

J. Org. Chem.

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Herein we demonstrate that the photolabile protecting group (PPG), the 1-[3-(diethylamino)-phenyl]ethyl (DEAPE) group, has dramatically different photochemical properties from the parent 3-(diethylamino)benzyl (DEABn) PPG. The new PPG, derived from DEABn by adding a methyl group to the benzylic carbon, has similar reactivity as DEABn in releasing alcohol in MeCN/water; however, it is more efficient than DEABn in releasing carboxylic acid. In particular, it can release carboxylic acid efficiently in aprotic solvents and the PPG itself converts to 3-diethylaminostyrene. Photochemical removal of DEAPE can also be conveniently carried out with sunlight. The results in this work suggest that there probably exist multiple reaction pathways in cleaving the benzylic C-O bond and they can be affected by the benzylic substitution and the reaction conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

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1-[3-(Diethylamino)phenyl]ethyl (DEAPE): A Photolabile Protecting Group for Hydroxyl and Carboxyl Groups

Ding

Wang

2018

J. Org. Chem.

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“…The viscous yellow oil was filtered through a short plug of silica gel (eluent = 15% ethyl acetate in hexane) and then purified via distillation in vacuo to afford the pure product as a clear oil, which crystallized on standing to afford 2.19 g of colorless plates (72%). Mp = 49−50 °C (lit 18b. 50 °C).…”

Section: Methodsmentioning

confidence: 99%

Photoresists with Reduced Environmental Impact: Water-Soluble Resists Based on Photo-Cross-Linking of a Sugar-Containing Polymethacrylate

Havard¹,

Vladimirov²,

Fréchet³

et al. 1998

Macromolecules

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A family of water-soluble, negative-tone, high-resolution, chemically amplified photoresists based on partially or fully deprotected poly(1,2:5,6-di-O-isopropylidene-3-O-methacryloyl-α-d-glucofuranose) is described. Both the molecular weight of the parent ketal-protected polymer and the extent of its deprotection to a water-soluble polymer containing 3-O-methacryloyl-d-glucopyranose repeat units must be carefully controlled to provide good coating and imaging properties. The two ketal protecting groups of the poly(1,2:5,6-di-O-isopropylidene-α-d-glucofuranose) have different reactivity, and their complete removal requires long reaction times under hydrolytic conditions. The detailed deprotection chemistry of the polymer is readily understood through model studies with the fully and partially protected analogues of the polymer pendant groups: 1,2:5,6-di-O-isopropylidene-α-d-glucofuranose and 1,2-isopropylidene-α-d-glucopyranose. When combined with a water-soluble photochemical precursor of acid such as (4-methoxyphenyl)dimethylsulfonium trifluoromethanesulfonate, films of the deprotected or partially deprotected poly(1,2:5,6-di-O-isopropylidene-3-O-methacryloyl-α-d-glucofuranose) undergo acid-catalyzed cross-linking. The enhanced performance of the partially deprotected polymers over that of poly(3-O-methacryloyl-d-glucopyranose) suggests that the presence of remaining hydrophobic groups that afford water dispersibility rather than full solubility may be key to their performance. Imaged negative-tone features as small as 0.2 μm are obtained with these materials that have sensitivities of ca. 30 mJ/cm2 with wholly aqueous casting and processing.

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“…The transformation relies on a photoinduced electron transfer process preferentially at HMPA but also at the acid residue and the products. [58] The versatility of this methodology was illustrated by the synthesis of deoxysugars from carbohydrate [59] and amino-glucoside esters. [60] Primary, secondary and even sterically hindered tertiary acetates or pivalates (Scheme 13, Eqn.…”

Section: Photoinduced-electron Transfer Deoxygenationmentioning

confidence: 99%

Tin-free Alternatives to the Barton-McCombie Deoxygenation of Alcohols to Alkanes Involving Reductive Electron Transfer

Chenneberg

Ollivier

2016

Chimia

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Echoing the recent celebration of the fortieth anniversary of the Barton-McCombie reaction, this review aims to explore another facet of radical processes for deoxygenation of alcohols by considering SET (single electron transfer) reduction of carboxylic ester, thiocarbonate and thiocarbamate derivatives. Various protocols have been developed relying on the use of organic and organometallic SET reagents, electrochemical conditions, photoinduced electron transfer processes and visible-light photoredox catalysis. Applications to the synthesis of molecules of interest provide a glimpse into the scope of these different approaches.

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On the mechanism and stereochemistry of hydrogen transfer involving photodeoxygenation of sugar esters in hexamethylphosphoric triamide/water

Cited by 19 publications

References 42 publications

1-[3-(Diethylamino)phenyl]ethyl (DEAPE): A Photolabile Protecting Group for Hydroxyl and Carboxyl Groups

1-[3-(Diethylamino)phenyl]ethyl (DEAPE): A Photolabile Protecting Group for Hydroxyl and Carboxyl Groups

Photoresists with Reduced Environmental Impact: Water-Soluble Resists Based on Photo-Cross-Linking of a Sugar-Containing Polymethacrylate

Tin-free Alternatives to the Barton-McCombie Deoxygenation of Alcohols to Alkanes Involving Reductive Electron Transfer

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