Photosensitized decarboxylative Michael addition through N-(acyloxy)phthalimides via an electron-transfer mechanism

Okada, Keiji; Okamoto, Kazushige; Morita, Naoto; Okubo, Katsura; Oda, Masaji

doi:10.1021/ja00024a074

Cited by 388 publications

(263 citation statements)

References 0 publications

Supporting

Mentioning

250

Contrasting

Unclassified

Order By: Relevance

“…The decarboxylative Giese-type radical addition of alkyl carboxylic acids and electron-poor alkenes has been reported by the MacMillan group. [46] In contrast to the seminal work by Okada and co-workers, [27] the authors were able to accomplish this transformation by an oxidative SET substrate activation strategy without the need for preactivation of the carboxylic acid (Scheme 12). Later, Akida and co-workers demonstrated that this transformation can also be accomplished with the organic photocatalyst 21 (see Scheme 10B).…”

Section: C(sp 3 )-Cooh and Derivatives Thereofmentioning

confidence: 92%

“…The first examples of decarboxylative radical formation aided by photocatalysis were disclosed in 1991 by Okada and co-workers in a ground-breaking paper that predates the modern explosion in this field by more than 15 years. [27] Here the authors employed N-(acyloxy)phthalimides 1 (Scheme 1), in conjunction with Ru(bpy) 3 Cl 2 and visible-light irradiation, to generate the key radical intermediates, which underwent subsequent Giese-type radical addition to various electron-deficient alkenes 2. [28] A reductive SET substrate activation process, reminiscent of modern photocatalytic cycles, was proposed.…”

Section: C(sp 3 )-Cooh and Derivatives Thereofmentioning

confidence: 99%

See 1 more Smart Citation

Visible‐Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp³)‐Substrates

Roslin

Odell

2017

Eur J Org Chem

View full text Add to dashboard Cite

Over the past decade, visible-light photocatalysis has emerged as one of the brightest and most dynamic fields in modern organic chemistry. By employing a transition-metal-or organic-dye-based photocatalyst in conjunction with a low-energy visible-light source, this synthetic manifold allows the facile generation of radical intermediates that can subsequently be directed through a wide range of transformations. Although

show abstract

Section: C(sp 3 )-Cooh and Derivatives Thereofmentioning

confidence: 92%

Section: C(sp 3 )-Cooh and Derivatives Thereofmentioning

confidence: 99%

Visible‐Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp³)‐Substrates

Roslin

Odell

2017

Eur J Org Chem

View full text Add to dashboard Cite

show abstract

“…Electrochemical processes have been developed using decarboxylative coupling (Kolbe process [17]) as well as oxidative decarboxylation (Hofer-Moest process [l 81) steps for the synthesis of complex target molecules. Non-electrochemical processes which have similar efficiency in producing C-centered radicals are the 'photo-Kolbe process ' [19], the Barton decarboxylation using thiohydroxamic esters as radical precursors [20], the intermolecular PET reduction of N-(acyloxy)phthalimides [21], and (for special cases) the direct photolytic decarboxylation [22]. The intramolecular PET of w-phthalimidoalkanoates with concomitant decarboxylation and C,C combination proceeds analogously to the PET of w-(alky1thio)- [23], w-(alkylamino)- [24], or o-[(trimethylsilyl)methoxy]-substituted [ 151 phthalimides.…”

mentioning

confidence: 99%

Synthesis of Medium‐ and Large‐Ring Compounds Initiated by Photochemical Decarboxylation of ω‐Phthalimidoalkanoates

Griesbeck

Henz

Krämer

et al. 1997

Helvetica Chimica Acta

View full text Add to dashboard Cite

The synthesis of a variety of hydroxylactams from w-phthalimidoalkanoates using a triplet-sensitized photodecarboxylation reaction initiated by intramolecular photo electron transfer is described. Ring sizes available by this method span from 4 (benzazepine-1,5-dione 7) to 26 (cyclodipeptide 26e). Ground-state template formation is proposed as the explanation for the high efficiency of this reaction and for the decrease in reactivity in the presence of organic bases instead of metal carbonates. The crucial step in this macrocyclization reaction seems to be the protonation of the intermediary ketyl radials (Scheme 4). Spacer groups investigated were alkyl chains (C3-Cll: 5c-h, lla, 12), ether (16, 18), ester (20, 22), and amide (26a-f) linkages. Within the detection limits, no dimeric (= decarboxylative coupling) products were observed, indicating the high preference for intravs. intermolecular photoelectron transfer. The C,C radical combination step proceeds with low stereoselectivity (cJ products 11 and 12) in contrast to comparable singlet reactions. Except for the lactones 22, all products were stable under the photolysis conditions. Prolonged irradiation of 22 led to the formation of the spiro compounds 23, probably via an intermediary acyliminium betaine (Scheme 8). One serious limitation of the decarboxylative macrocyclization is its incompatibility with the glycine spacer (as in 27a and 27b), probably the consequence of a strong intramolecular H-bond (Scheme 10).

show abstract

“…Over 20 years ago Okada demonstrated that, when exposed to visible light, Ru(bpy) 3 Cl 2 (bpy = 2, 2′-bipyridine), and the hydrogen-donor 1-benzyl-1,4-dihydronicotinamide, such compounds are transformed in the presence of α,β-unsaturated ketones to products of conjugate addition in excellent yield. [14] We noted that in a single instance a tertiary radical (1-admantanyl) had been coupled effectively. Surprisingly, the use of (N-acyloxy)phthalimides as radical precursors in conjugate addition reactions has not been described since this initial disclosure, and their photosensitized cleavage has only rarely been reported in any form.…”

mentioning

confidence: 96%

A Concise Synthesis of (−)‐Aplyviolene Facilitated by a Strategic Tertiary Radical Conjugate Addition

Schnermann

Overman

2012

Angewandte Chemie

View full text Add to dashboard Cite

Aplyviolene (1) and macfarlandin E (2, Figure 1A) are representative of the more complex members of the rearranged spongian diterpene class of natural products. [1,2] These diterpenes are structurally defined by attached cis-perhydroazulene and 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one fragments. The substantial challenge in assembling these structures centers on the construction of the sensitive bicyclic lactone subunit and the formation of the C8-C14 σ-bond joining the two ring systems, a challenge augmented by the quaternary nature of C8. [3] We previously reported preparation of the lactone subunits of 1 and 2 by the synthesis of truncated congeners 3 and 4 ( Figure 1A), [4] as well as the first total synthesis of aplyviolene (outlined in Figure 1B). [5] In this latter effort, the key C8-C14 σ-bond was formed by Michael addition of tertiary enolate 5 to enone 6. [6] Subsequent elaboration of product 7 provided intermediate 8, which was converted to (−)-aplyviolene along the lines of our earlier synthesis of 3. Undesirable aspects of this first-generation synthesis are the lengthy preparation of the cis-perhydroazulene unit and the need to remove the extraneous ketone carbonyl group from the product of the fragment-coupling step.As described in the accompanying communication, [7] our initial attempt to streamline the synthesis by using a tertiary organocuprate derived from cis-perhydroazulene nitrile 9 in the key fragment coupling was prevented by exclusive formation of adduct 11, which is epimeric to aplyviolene at the critical quaternary carbon stereocenter ( Figure 1C). This unexpected stereochemical outcome of the organocuprate conjugate addition reaction provoked consideration of an alternative strategy in which the C8-C14 σ-bond would be formed by the union of the tertiary radical 12 and enone 13 ( Figure 1D, X = leaving group). Reductive silylation of the coupled product 14 would then provide enoxy silane 8, an advanced intermediate in the synthesis of (−)-aplyviolene. Despite the many advances in stereoselective radical chemistry, [ 8 ] bimolecular reactions that transform trialkylsubstituted tertiary radicals to stereogenic quaternary carbons are extremely rare.

show abstract

Photosensitized decarboxylative Michael addition through N-(acyloxy)phthalimides via an electron-transfer mechanism

Cited by 388 publications

References 0 publications

Visible‐Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp³)‐Substrates

Visible‐Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp³)‐Substrates

Synthesis of Medium‐ and Large‐Ring Compounds Initiated by Photochemical Decarboxylation of ω‐Phthalimidoalkanoates

A Concise Synthesis of (−)‐Aplyviolene Facilitated by a Strategic Tertiary Radical Conjugate Addition

Contact Info

Product

Resources

About

Photosensitized decarboxylative Michael addition through N-(acyloxy)phthalimides via an electron-transfer mechanism

Cited by 388 publications

References 0 publications

Visible‐Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp3)‐Substrates

Visible‐Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp3)‐Substrates

Synthesis of Medium‐ and Large‐Ring Compounds Initiated by Photochemical Decarboxylation of ω‐Phthalimidoalkanoates

A Concise Synthesis of (−)‐Aplyviolene Facilitated by a Strategic Tertiary Radical Conjugate Addition

Contact Info

Product

Resources

About

Visible‐Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp³)‐Substrates

Visible‐Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp³)‐Substrates