Generation of aminoacyl radicals from 1-carbamoyl-1-methylcyclohexa-2,5- dienes: a new tin-free homolytic route to β- and γ-lactams

Jackson, Leon V.; Walton, John C.

doi:10.1039/b007454n

Cited by 51 publications

(26 citation statements)

References 12 publications

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“…A range of ring sizes can be achieved with this chemistry. As has been previously demonstrated by others,9d,e,i–l carbamoyl radicals efficiently cyclize to form four‐membered rings (Table 1, entries 1 and 2). In the case of β lactam 13 , a single diastereomeric adduct is formed, the configuration of which has been proven by X‐ray crystallography.…”

Section: Methodssupporting

confidence: 76%

Cadmium and zinc localization by SIMS in leaves of Populus deltoides (cv. Lena) grown in a metal polluted soil

Migeon¹,

Audinot²,

Eybe

et al. 2011

Surface & Interface Analysis

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a Poplar (Populus) species can relatively accumulate high concentrations of heavy metals such as cadmium and zinc in their aboveground tissues. Cd accumulation in poplar is 30 times higher as compared to other woody species. Zn concentrations in leaves ranged from 200 to 1000 mg kg −1 dry weight (DW) and Cd concentrations from 10 to 70 mg kg −1 DW on metal polluted sites. These plants possess effective mechanisms for heavy metal translocation into aerial parts. However cellular localization of zinc and cadmium is still unknown in these species. In order to elucidate the precise localisation of these elements, leaves of poplar (Populus deltoides cv. Lena) was grown on metal polluted soil and analysed by SIMS. Using primary gallium source (FIB) mounted on IMS-6f, it was possible to performed secondary ions positives images with a lateral resolution above to 100 nm. In this study, SIMS analysis has been performed on cross section of leaves. Results were compared with global measurement performed by ICP-AES on reference sample (no contaminated) and poplar exposed to metals. Elemental maps of cadmium and zinc were obtained which revealed the high concentrations of metals in both the mesophyll and in the epidermal cell layer.

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Section: Methodssupporting

confidence: 76%

Cadmium and zinc localization by SIMS in leaves of Populus deltoides (cv. Lena) grown in a metal polluted soil

Migeon¹,

Audinot²,

Eybe

et al. 2011

Surface & Interface Analysis

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show abstract

“…[ 41 ]–[ 45 ] However, at the outset of this work we were aware of only one additional example in the literature, related to the cyclization of 3 to 4 , for the synthesis of a ring-fused system. [ 42 ]…”

Section: Resultsmentioning

confidence: 99%

Carbamoyl Radical‐Mediated Synthesis and Semipinacol Rearrangement of β‐Lactam Diols

Betou

Male

Steed

et al. 2014

Chemistry A European J

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In an approach to the biologically important 6-azabicyclo[3.2.1]octane ring system, the scope of the tandem 4-exo-trig carbamoyl radical cyclization—dithiocarbamate group transfer reaction to ring-fused β-lactams is evaluated. β-Lactams fused to five-, six-, and seven-membered rings are prepared in good to excellent yield, and with moderate to complete control at the newly formed dithiocarbamate stereocentre. No cyclization is observed with an additional methyl substituent on the terminus of the double bond. Elimination of the dithiocarbamate group gives α,β- or β,γ-unsaturated lactams depending on both the methodology employed (base-mediated or thermal) and the nature of the carbocycle fused to the β-lactam. Fused β-lactam diols, obtained from catalytic OsO4-mediated dihydroxylation of α,β-unsaturated β-lactams, undergo semipinacol rearrangement via the corresponding cyclic sulfite or phosphorane to give keto-bridged bicyclic amides by exclusive N-acyl group migration. A monocyclic β-lactam diol undergoes Appel reaction at a primary alcohol in preference to semipinacol rearrangement. Preliminary investigations into the chemo- and stereoselective manipulation of the two carbonyl groups present in a representative 7,8-dioxo-6-azabicyclo[3.2.1]octane rearrangement product are also reported.

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“…Cleavage of the N -Boc group was accompanied by dehydration of the cyclic aminal, and acylation of the free amine with 1-methyl-2,5-cyclohexadiene-1-carbonyl chloride to give 140 . The specific acylating agent 139 was chosen due to the fact that it had been reported as an efficient acyl radical precursor 31. In fact, when 140 was heated with tert -amyl peroxybenzoate, the aminoacyl radical 141 is presumably formed, which then attacks the more-substituted carbon of the enamide C-C double bond and expels the phenlthiyl radical to give the bicyclo[2.2.2]diazaoctane core structure 142 .…”

Section: Other Synthetic Strategiesmentioning

confidence: 99%

Synthetic approaches to the bicyclo[2.2.2]diazaoctane ring system common to the paraherquamides, stephacidins and related prenylated indole alkaloids

Miller

Williams

2009

Chem. Soc. Rev.

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Generation of aminoacyl radicals from 1-carbamoyl-1-methylcyclohexa-2,5- dienes: a new tin-free homolytic route to β- and γ-lactams

Abstract: Radical induced homolyses of 1-carbamoyl-1-methylcyclohexa-2,5-dienes took place cleanly to yield aminoacyl radicals, with no competition from the alternative dissociation to methyl radicals: band g-lactams were obtained from ring closures of suitably unsaturated model compounds.

Cited by 51 publications

References 12 publications

Cadmium and zinc localization by SIMS in leaves of Populus deltoides (cv. Lena) grown in a metal polluted soil

Cadmium and zinc localization by SIMS in leaves of Populus deltoides (cv. Lena) grown in a metal polluted soil

Carbamoyl Radical‐Mediated Synthesis and Semipinacol Rearrangement of β‐Lactam Diols

Synthetic approaches to the bicyclo[2.2.2]diazaoctane ring system common to the paraherquamides, stephacidins and related prenylated indole alkaloids

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