Enantioselective total syntheses of cyclopropane amino acids: Natural products and protein methanologs

Jimenez, José; Rifé, Joan; Ortuño, Rosa M.

doi:10.1016/0957-4166(96)00038-9

Cited by 63 publications

(37 citation statements)

References 25 publications

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“…Such processes have been observed with sodium thiomethoxide as the nucleophile,317,318 as well as in Arbuzov reactions (Scheme 134) 319. It is worth noting that the reactivity can be tuned in favour of the desired S N 2 reaction.…”

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confidence: 90%

“…It is worth noting that the reactivity can be tuned in favour of the desired S N 2 reaction. Factors that have been reported to disfavour the unwanted S N 2'-type reaction are steric hindrance around the cyclopropane carbon atom bearing the nitrogen substituent, the choice of the nucleophile, 317 reverse addition,318 and substitution of the nitrogen atom with more electronwithdrawing groups such as the trifluoroacetate group. 319 Scheme 134.…”

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confidence: 99%

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Ring-opening, cycloaddition and rearrangement reactions of nitrogen-substituted cyclopropane derivatives

Rassadin

Six

2016

Tetrahedron

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confidence: 90%

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confidence: 99%

Ring-opening, cycloaddition and rearrangement reactions of nitrogen-substituted cyclopropane derivatives

Rassadin

Six

2016

Tetrahedron

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“…Among these, compound 19 (R ¼ Cbz and Boc) was prepared in 100% yield and photochemically transformed into compound 20 in quantitative yield. The latter was used for the total synthesis of (À)-allo-coronamic acid, (À)-allo-norcoronamic acid, (À)-(Z)-2,3-methanohomoserine, and (À)-(Z)-2,3-methanomethionine [22]. Similarly, the photochemical reaction of pyrazoline 21 led to the key cyclopropane intermediate 22 for the synthesis of (AE)-carnosadine, a marine natural product isolated from the red alga Grateloupia carnosa [21a].…”

Section: 22mentioning

confidence: 99%

CarbonCarbon Bond Formation by the Photoelimination of Small Molecules in Solution and in Crystals

Shiraki

2009

Handbook of Synthetic Photochemistry

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The formation of CÀC bonds is arguably the most important reaction in organic synthesis. While many strategies have been developed to link organic fragments with a wide range of thermal processes, photochemical syntheses based on the elimination of a small molecule, X (Scheme 2.1), offer significant advantages when the desired structures are highly strained or hindered. In this chapter, we will describe examples of the generation of CÀC bonds through the photoinduced extrusion of small molecules such as N 2 , CO 2 , CO, and SO 2 , as well as the formal extrusion of S atoms. After describing the most general mechanistic aspects covering these reactions and the current scope and limitations, we will illustrate examples involving these reactions in solution. Following that, we will describe a strategy based on the use of crystalline solids that helps to control the fate of the reaction intermediates. Finally, we will illustrate the use of crystalline ketones (X¼CO) as one of the most promising general methods for the synthesis of compounds with all-carbon adjacent stereogenic quaternary centers.The photoelimination of a small stable molecule X accompanied by the formation of a new CÀC bond could, in principle, take place in a concerted manner through cyclic transition states with simultaneous bond-breaking and bond-making steps that follow trajectories determined by orbital symmetry considerations. However, as it pertains to photodecarbonylation reactions, theoretical analysis on the formation of hydrogen and CO from formaldehyde suggests that the concerted process is significantly less likely than the stepwise cleavage of the HÀC(O)ÀH bonds [1]. Similar conclusions have been made for the elimination of N 2 and H 2 from simple diazene (HN¼NH) [2]. In fact, evidence for concerted reactions is available only in a handful of cases (vide infra). Most examples involve a four-step process that starts with electronic excitation (step 1) and is followed by an a-cleavage reaction (step 2) to give a primary biradical or radical pair (BR-1). Subsequent dissociation of the small molecule X (step 3) results in the formation of the secondary biradical or radical pair (BR-2), which is followed by radical-radical combination to give the desired product (step 4).Handbook of Synthetic Photochemistry. Edited

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“…The ring moieties are practically planar, with maximum deviations of 0.0158 (1) and 0.0210(1) ä for C(1) and C(13), respectively. The dihedral angle between the least-squares planes of the two rings is 63.758.…”

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confidence: 99%

“…± Conformationally restricted a-amino acids [1] are important tools for studying the spatial requirements for receptor affinity and the biological activity of natural amino acids and peptides [2]. Replacement of natural amino acids in bioactive peptides by conformationally restricted amino acids has led to a better understanding of their bioactive conformations [3] [4].…”

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confidence: 99%

Enantioselective Synthesis of 2‐(2‐Arylcyclopropyl)glycines: Conformationally Restricted Homophenylalanine Analogs

Demir

Şeşenoğlu

Ülkü

et al. 2004

Helvetica Chimica Acta

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Dedicated to Professor Wolfgang Steglich on the occasion of his 70th birthdayStarting from simple aromatic aldehydes and acetylfuran, (E)-1-(furan-2-yl)-3-arylprop-2-en-1-ones (2) were synthesized in high yields. Cyclopropanation of the CC bond with trimethylsulfoxonium iodide (Me 3 SO I À ) furnished (furan-2-yl)(2-arylcyclopropyl)methanones 3 in 90 ± 97% yields. Selective conversion of cyclopropyl ketones to their (E)-and (Z)-oxime ethers 5 and oxazaborolidine-catalyzed stereoselective reduction of the CN bond followed by separation of the formed diastereoisomers, furnished (2-arylcyclopropyl)(furan-2-yl)methanamines 6 in optically pure form and high yield. Oxidation of the furan ring of (S,S,S)-, (S,R,R)-, (R,S,S)-, and (R,R,R)-6a afforded the four stereoisomers of a-(2-phenylcyclopropyl) glycine (1a).

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Enantioselective total syntheses of cyclopropane amino acids: Natural products and protein methanologs

Cited by 63 publications

References 25 publications

Ring-opening, cycloaddition and rearrangement reactions of nitrogen-substituted cyclopropane derivatives

Ring-opening, cycloaddition and rearrangement reactions of nitrogen-substituted cyclopropane derivatives

CarbonCarbon Bond Formation by the Photoelimination of Small Molecules in Solution and in Crystals

Enantioselective Synthesis of 2‐(2‐Arylcyclopropyl)glycines: Conformationally Restricted Homophenylalanine Analogs

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