Rhodium(II)‐Catalyzed One‐Pot Four‐Component Synthesis of Functionalized Polyether Macrocycles at High Concentration

Abstract

Vollkommen unerwartet wurde die Rhodium(II)-katalysierte templatfreie Makrocyclisierung von vier Einzelkomponenten in einem Reaktionsgefäß effizienter, wenn die Konzentration erhöht wurde. Daher kondensierten α-Diazo-β-ketoester mit 1,4-Dioxan, THF oder Tetrahydropyran als Lösungsmittel zu 16- bis 18-gliedrigen Polyethermakrocyclen in bis zu 75 % Ausbeute (siehe Schema; R=Me, Et, PhCH2CH2, Allyl, PhCH[doublbond]CH2

Excimer‐Based On‐Off Bis(pyreneamide) Macrocyclic Chemosensors

“…In our group, a series of bis(pyreneamide) macrocycles was also prepared, namely compounds 16C4‐Pyr 2 , 18C4‐Pyr 2 , 20C4‐Pyr 2 , and 18C6‐Pyr 2 ( Figure , Pyr = 1‐pyrenyl) . These derivatives are synthesized in two steps from THF, THP, oxepane, and 1,4‐dioxane, respectively . The macrocycles are globally planar and act as a platform; the amide units being oriented perpendicularly to the mean plane.…”

Macrocyclization of Oxetane Building Blocks with Diazocarbonyl Derivatives under Rhodium(II) Catalysis

“…These intermediates are readily prepared by reactions of ethers and α‐diazocarbonyls under photoirradiation, electrophilic activation, or metal catalysis 7. 9 For instance, 18‐membered macrocycles were recently prepared in a single step by the condensation of two α‐diazo‐β‐ketoesters and two cyclic ethers (1,4‐dioxane, tetrahydropyrane) in the presence of [Rh 2 (OAc) 4 ] or [Rh 2 (Oct) 4 ] 9d. A dimerization under high concentration of two oxonium ylide intermediates was postulated to explain the reactivity.…”

“…A structural analysis was performed and confirmed unambiguously the chemical nature of the macrocyclic structure (Figure 1). Noticeably, compounds 3 h (R 2 =Ph) and 3 i (R 2 = i Pr) are obtained in good yields whereas little or no amount of 18‐membered macrocycles were obtained when substrates 2 h and 2 i were reacted in 1,4‐dioxane as solvent 9d. Two other substrates were tested.…”

Twin Polymerization: A Unique and Efficient Tool for Supporting Silver Nanoparticles on Highly Porous Carbon and Silica

“…The transition metal‐catalyzed decomposition of diazo compounds is a powerful method to promote synthetic transformations including not only cyclopropanation, dimerization, insertion, dipolar addition, ylide generation (and subsequent rearrangement) reactions,1 but also macrocycle synthesis 2. In this context, our group has previously reported a four‐component synthesis of 16‐ and 18‐membered macrocycles using α‐diazo‐β‐keto esters and simple cyclic ethers as reactants (Scheme ) 3,4. This Rh(II)‐catalyzed macrocyclization, which is a formal [3+6+3+6]5 condensation, displays interesting reactivity aspects including the need for a high concentration in the diazo reactants (∼1 M) and a perfect regioselectivity.…”

“…Under mild reaction conditions (20 or 60 °C), a large selection of diazo‐keto ester reagents can be used to afford macrocyclic products in yields up to 75%. However, in this initial study,3 only simple THF, THP (tetrahydropyran) and 1,4‐dioxane were utilized as co‐reactants. The side chains linking the dioxobutenoate motifs were therefore devoid of substituents.…”