Synthesis of the Tetracyclic ABCD Ring Systems of Madangamines D–F

Abstract

Synthesis of the tetracyclic cores of madangamines D-F was achieved, featuring a reductive radical process from an ethoxycarbonyldichloroacetamide to build the morphan nucleus, a Mitsunobu-type aminocyclization toward the common diazatricyclic intermediate, and ring-closing metathesis reactions for the macrocyclization step leading to the 13- to 15-membered rings.

Rationally Designed Supramolecular Organic Hosts for Benzo[a]pyrene Binding and Detection

“…Double macrocyclization proceeded either by a phase-transfer etherification reaction (for compounds 5 and 6) or by a double Mitsunobu reaction (for compounds 7-10) to obtain the target compounds (Scheme 1). [20] In our case, the Mitsunobu macrocyclizations proceeded in substantially higher yields (20-42 %, with an average yield of 33 %) compared to the etherification macrocyclization approach (5-6 % yield), leading to yields that are in line with or better than literature-reported yields for analogous macrocyclization reactions. [20] In our case, the Mitsunobu macrocyclizations proceeded in substantially higher yields (20-42 %, with an average yield of 33 %) compared to the etherification macrocyclization approach (5-6 % yield), leading to yields that are in line with or better than literature-reported yields for analogous macrocyclization reactions.…”

Photoredox catalysis in the synthesis of γ- and δ-lactams from N-alkenyl trichloro- and dichloroacetamides

“…2 On the other hand, trichloroacetamides bearing a suitably located double bond have been widely used to access lactams using radical chemistry. 3 Thus, free radical cyclization protocols mediated by organostannane 4 or organosilane 5 reagents ( e.g. Bu 3 SnH or HSi(SiMe 3 ) 3 ), as well as those in the presence of copper, 6 ruthenium 7 or iron 8 complexes, have been successfully used to access mainly γ- and δ-lactams.…”

Oxamidation of Unsaturated O-Alkyl Hydroxamates: Synthesis of the Madangamine Diazatricylic (ABC Rings) Skeleton

“…An alternative approach to ring A formation has been developed by Diaba and Bonjoch, who employed the 6- exo-trig cyclization of 3-aza-6-heptenyl radical 10 to form the C-9/C-11 bond ( B , Figure ). Routes to the ABC nucleus involving ring C formation been reported by Chida, , who used the N -acyliminium cyclization of propargyl silane 11 , and Marazano, who has reported the biomimetic condensation of dihydropyridinium ion 12 and the sodium salt of diethylacetonedicarboxylate to simultaneously establish the C-2/C-3, C-5/C-11 and C-6/N-7 bonds ( C , Figure ). …”