Organocatalytic Oxidative Dimerization of Alcohols to Esters

Abramovich, Adi; Toledo, Hila; Pisarevsky, Evgeni; Szpilman, Alex M.

doi:10.1055/s-0032-1317018

Cited by 23 publications

(7 citation statements)

References 3 publications

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“…The diol A1 was obtained from a ring-opening reaction of cyclohexene oxide with propylene glycol, which was next treated with trichloroisocyanuric acid (TCCA) and 2,4,6-collidine in presence of (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO) as a catalyst to yield M1 at 37% overall yield on the gram scale. 78 The hydroxyl acid A2 was obtained by using 3-mercaptopropionic acid as a nucleophile. Lactonization of A2 afforded monomer M2 in 56% overall yield for two steps on a 10 g scale.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Stereoselective Ring-Opening Polymerization of Lactones with a Fused Ring Leading to Semicrystalline Polyesters

et al. 2022

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Monomer design is vital in the development of polymers with desired thermal and mechanical properties. Here, we prepared two monomers (M1, trans-octahydro-2H-benzo [b][1,4]dioxepin-2-one and M2, trans-octahydro-2H-benzo[b][1,4]oxathiepin-2-one) based on 1,5-dioxepan-2-one (DXO) and 1,4-oxathiepan-7-one (OTO) by incorporating trans-fused cyclohexyl rings. These monomers featured living ring-opening polymerization-yielding polymers with predictable molecular weights while maintaining low D̵ values. To gain a better understanding of the influence of polymer tacticity on polymer properties, a series of polymers with variable tacticities were prepared under various conditions. Their thermal property studies revealed that increasing the P r value to 91% of P(M2) led to an emerging melting-transition temperature of 101 °C. Copolymerization of M1 and M2 allowed us to obtain a well-defined diblock polymer P(M2)-b-P(M1) and random copolymer P(M1-co-M2) with distinct thermal behaviors. Excitingly, oxidation of P(M2) resulted in an increase of the glass transition temperature from 18 to 112 °C. Hydrolysis of these polymers to corresponding hydroxyl acids and subsequent lactonization reactions enabled a closed-loop life cycle of P(M)s.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Stereoselective Ring-Opening Polymerization of Lactones with a Fused Ring Leading to Semicrystalline Polyesters

et al. 2022

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“…On the basis of the control experiments and according to that reported for similar cases, 18−21 the probable reaction pathway is put forward, as shown in Scheme 4. First, TCCA reacts with TEMPO to form N -oxoammonium ion I , which oxidizes the primary alcohol through intermediate II to the corresponding aldehyde IV , giving hydroxylamine III .…”

Section: Resultsmentioning

confidence: 97%

“…TCCA is a commercially available and very cheap oxidant. 15−17 The combination of TEMPO and TCCA has been used catalytically and stoichiometrically for the oxidation of primary alcohols to aldehydes, 18 α-chloroaldehydes, 19 carboxylic acids, 20 esters, 21 and so on.…”

Section: Introductionmentioning

confidence: 99%

TEMPO-Catalyzed Direct Conversion of Primary Alcohols to α-Chloroacetals with TCCA Both as an Oxidant and a Chlorination Reagent

Feng

Feng²,

Liu

et al. 2018

ACS Omega

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Multistep reactions are often required for the transformation of alcohols to α-chloroacetals via the unstable intermediates aldehydes or α-halo aldehydes. Herein, we report a simplified procedure for practical synthesis of α-chloroacetals using 2,2,6,6-tetramethylpiperidine-1-oxyl as a catalyst and trichloroisocyanuric acid both as an oxidant and a chlorination reagent. The reaction is one-pot, solvent-free and high-yielding. In addition, the α-chloroacetals have been transformed to enol ethers through the elimination reaction in the presence of sodium.

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“…For our studies we chose trichloroisocyanuric acid (TCCA) as terminal oxidant for TEMPO-catalyzed oxidative esterification of alcohols because it is a very cheap and non-toxic reagent and has been used with success in a number of TEMPO-catalyzed oxidation reactions. 17,20 After some experimentation on the model substrate 1f, the HFIP ester 2f could be obtained in 82% yield by treatment of the alcohol 1f in CH 2 Cl 2 21 with TEMPO (5 mol%) and TCCA (1.2 equiv) added by portions at 0 °C followed, after consumption of the alcohol, by HFIP alcohol (2 equiv) and pyridine (4 equiv) and stirring the suspension for 30 minutes at room temperature (Table 1, entry 6). The resulting ester was easily purified by filtration of the suspension through a pad of silica gel.…”

Section: Syn Lettmentioning

confidence: 99%

“…15,16 Later on, Szpilman and co-workers showed that this oxidation could work as well by using a catalytic amount of TEMPO and a terminal oxidant. 17 They also reported a new method of mixed anhydride synthesis from aldehydes and pivalic acid with a TEMPO/t-BuOCl/ pyridine system and these mixed anhydrides were further transformed to esters and amides via a one-pot procedure. 18 In 2013, Leadbeater and co-workers reported the oxidative esterification of aldehydes to HFIP esters using the Bobbitt oxidation procedure.…”

Section: -98% 53-93%mentioning

confidence: 99%

TEMPO-Catalyzed Oxidative Amidation of Alcohols via Hexafluoroisopropyl Esters

Vatèle

2015

Synlett

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Stepwise oxidative amidation of alcohols using trichloroisocyanuric acid, a catalytic amount of TEMPO in combination with pyridine and hexafluoroisopropyl (HFIP) alcohol followed by amines is described. This procedure used HFIP esters as activating esters which were found to be very efficient acylating agents for amide bond formation. This process is compatible with a number of functional groups and acid-sensitive protecting groups.The amide bond is one of the most important linkages in organic synthesis and constitutes the key motif in peptides, natural products, agrochemicals, pharmaceuticals and polymers. 1 It is estimated that more than 25% of known drugs contain an amide functional group. 2 The conventional approach for the synthesis of amides is the coupling of activated carboxylic acid derivatives with amines. 3 However, these methods have the drawbacks of generating a stoichiometric amount of by-products and employing hazardous reagents. An attractive alternative redox approach to amide formation is acylation of amines from aldehydes or even better alcohols. 4 Indeed, the direct amidation of alcohols with amines through aldehydes is a potentially elegant alternative pathway since it uses cheap, abundant and stable materials. Milstein and co-workers were the first to report a direct amidation of alcohols using a dehydrogenative pathway with a ruthenium pincer complex. 5 Other metalcatalyzed oxidation of alcohols to amides were further described. 6 Amidation via N-hydroxysuccinimide esters was reported using IBX 7a or TBHP in the presence of NBu 4 I 7b as oxidants. Although these systems provide a new route to amides, they suffer from drawbacks such as narrow substrate scope, 6,7a hydrogenation of unsaturated compounds 5 or low yields. 7a In continuation of our interest in the development of novel synthetic applications of TEMPO/co-oxidants systems, 8 we envisaged that amides could be synthesized from alcohols by a TEMPO-catalyzed tandem oxidation process (TOP) 9 through an active ester. In 2012, Barbas and coworkers developed a tetrabutylammonium iodide catalyzed amidation and esterification of aldehydes with activating agents by a cross-coupling strategy. 10 Among the active intermediates studied, we focused our attention to hexafluoroisopropyl (HFIP) esters. These active esters were only used sparingly in organic synthesis as acylating agents particularly in the synthesis of peptides, 11 amides, 12 and in lactamization 13 and transesterification 14 reactions. A major advantage of HFIP esters compared to other active esters is that hexafluoroisopropanol formed during the substitution reaction is easy to remove by simple evaporation because of its low boiling point (58 °C). In 2004, Bobbitt and co-workers reported the first example of oxidative dimerization of alcohols to esters using a large excess of an oxoammonium salt in the presence of pyridine, a crucial reagent for the oxidation to take place. 15,16 Later on, Szpilman and co-workers showed that this oxidation could work as well by using a catalyt...

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Organocatalytic Oxidative Dimerization of Alcohols to Esters

Abstract: 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) catalyzes the direct oxidation of primary alkyl alcohols to symmetric esters at 1-2 mol% loadings. These rapid reactions take place at room temperature to afford the products in yields of 55-99%.

Cited by 23 publications

References 3 publications

Stereoselective Ring-Opening Polymerization of Lactones with a Fused Ring Leading to Semicrystalline Polyesters

Stereoselective Ring-Opening Polymerization of Lactones with a Fused Ring Leading to Semicrystalline Polyesters

TEMPO-Catalyzed Direct Conversion of Primary Alcohols to α-Chloroacetals with TCCA Both as an Oxidant and a Chlorination Reagent

TEMPO-Catalyzed Oxidative Amidation of Alcohols via Hexafluoroisopropyl Esters

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Organocatalytic Oxidative Dimerization of Alcohols to Esters

Abstract: 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) catalyzes the direct oxidation of primary alkyl alcohols to symmetric esters at 1-2 mol% loadings. These rapid reactions take place at room temperature to afford the products in yields of 55-99%.

Cited by 23 publications

References 3 publications

Stereoselective Ring-Opening Polymerization of Lactones with a Fused Ring Leading to Semicrystalline Polyesters

Stereoselective Ring-Opening Polymerization of Lactones with a Fused Ring Leading to Semicrystalline Polyesters

TEMPO-Catalyzed Direct Conversion of Primary Alcohols to α-Chloroacetals with TCCA Both as an Oxidant and a Chlorination Reagent

TEMPO-Catalyzed Oxidative Amidation of Alcohols via Hexa­fluoroisopropyl Esters

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TEMPO-Catalyzed Oxidative Amidation of Alcohols via Hexafluoroisopropyl Esters