Construction of Fused Tropone Systems Through Intramolecular Rh(I)-Catalyzed Carbonylative [2+2+2+1] Cycloadditon of Triynes.

"Tropone" is a non-benzenoid aromatic skeleton that can be found in a variety of natural products. This cyclohepta-2,4,6-trien-1-one skeleton appears simple, but there have been no straightforward ways to construct this molecular architecture. It is conceivable that this molecule can be constructed via a higher order cycloaddition of three acetylene units and CO, but such process was not known until we have discovered that the carbonylative [2+2+2+1] cycloaddition of triynes can take place in the presence of a Rh complex catalyst and CO.

Synthesis of Colchicinoids and Allocolchicinoids through Rh(I)-Catalyzed [2+2+2+1] and [2+2+2] Cycloadditions of o-Phenylenetriynes with and without CO.

The nonbenzenoid aromatics, tropones and tropolones, are found in various natural products such as colchicine and hinokitol, which possess significant biological activities. The traditional methods to construct the tropone skeletons include oxidation of cycloheptatriene and [4+3] cycloadditions. In addition, the total synthesis of colchicine and its analogues requires laborious organic transformations in the formations of 6-7-7 fused-ring systems.

Design, Synthesis, and Biological Evaluations of Asymmetric Bow-Tie PAMAM Dendrimer-Based Conjugates for Tumor-Targeted Drug Delivery.

A unique asymmetric bow-tie poly(amidoamine) (PAMAM) dendrimer (ABTD) scaffold was designed and developed as a well-defined macromolecular carrier for tumor-targeted drug delivery. The ABTD scaffold in this study consists of a G3-half-dendron (G3-HD) unit and a G1-half-dendron (G1-HD) unit, bearing thiol moiety in each unit and a bis(maleimide) linker unit, which undergo sequential thiol-maleimide coupling to assemble the scaffold. This assembly methodology is applicable to all other combinations of different generations of PAMAM dendrimers.