Synthesis of Primitive Dendrimer Systems Bearing Bicyclo[3,2,0]Hept‐6‐en‐6‐yl Groups via Unique Au‐catalyzed [2+2] Cyclization

Abstract

Propargylic pivaloates bearing an alkynyl group at a three-carbon tether under the gold catalysis would undergo [3,3] rearrangements of propargylic pivaloates followed by tandem [2+2] cyclization to give the corresponding 6-acylbicyclo[3,2,0]hept-6-ens. In continuing work, we prepared various substrates bearing two arms of alkyne-propargylic pivaloates to explore primitive dendrimer concept bicyclic compounds. Finally, we could obtain a series of diasteromeric compounds bearing two arms of 6-acylbicyclo[3,2,0] hept-6-ene groups in high yields.

Gold-Catalyzed Synthesis of Small Rings

“…The same group broadened the scope of dimeric bicycles by using 1,7-diyne pivalates linked by a variety of other aryl rings. 748 …”

“…The same group broadened the scope of dimeric bicycles by using 1,7-diyne pivalates linked by a variety of other aryl rings. 748 The group of Chan developed a gold(I)-catalyzed cycloisomerization of N-tethered 1,7-diyne benzoates 733. Here, substrates bearing terminal alkynes afforded N-heterocyclecontaining cyclobutenes 734 in a regio-and diastereoselective manner (Scheme 161A).…”

“…Under the same conditions, when two 1,7-diyne pivalate scaffolds were linked by a phenyl moiety, dimeric bicycles of type 732c were obtained by a 2-fold 1,3-acyloxy shift/[2 + 2] cycloaddition sequence. The same group broadened the scope of dimeric bicycles by using 1,7-diyne pivalates linked by a variety of other aryl rings …”

Electrochemically induced deposition of hydroxyl‐terminated poly(amidoamine) dendrimers encapsulating Pt nanoparticles on indium tin oxide for enhanced electrochemiluminescence

“…Dendrimers have been highlighted as monodisperse polymeric materials with nanometer‐scale dimension, 1–2 which is attractive for their use in analytical applications as well as other applications, such as drug delivery, nanomaterial synthesis, surface coating, and disease diagnosis and therapy 3–11 . Recently, we have reported the electrochemical surface modification of electrode materials including glassy carbon, carbon nanotube, and indium tin oxide (ITO) via electro‐oxidative coupling of amine‐terminated dendrimers 12–14 .…”

Gold-Catalyzed Homogeneous (Cyclo)Isomerization Reactions

“…In a related work, the [Ph 3 PAu] + -activation of propargyl ester motifs promotes the 1,3-acyl shift/[2+2]/hydrolysis cascade reaction of the diynes 87 furnishing a diastereomeric mixture of the polycyclic systems 88 (Figure 8D). The authors were able to resolve the diasteromeric mixture and even extend this protocol to other diynes in which the pivaloate substituents are located at positions 3 and 3' (Lee et al, 2018).…”