Reiterative Mechanisms of Retinoic Acid Signaling during Vertebrate Heart Development

Tightly-regulated levels of retinoic acid (RA) are critical for promoting normal vertebrate development. The extensive history of research on RA has shown that its proper regulation is essential for cardiac progenitor specification and organogenesis. Here, we discuss the roles of RA signaling and its establishment of networks that drive both early and later steps of normal vertebrate heart development. We focus on studies that highlight the drastic effects alternative levels of RA have on early cardiomyocyte (CM) specification and cardiac chamber morphogenesis, consequences of improper RA synthesis and degradation, and known effectors downstream of RA. We conclude with the implications of these findings to our understanding of cardiac regeneration and the etiologies of congenital heart defects

Triflic Acid Mediated Sequential Cyclization of ortho-Alkynylarylesters with Ammonium Acetate

A triflic acid (TfOH) mediated sequential cyclization of ortho-alkynylarylesters and ammonium acetate (NH4OAc) was reported. The reaction took place via a Brønsted acid-mediated intramolecular cyclization of ortho-alkynylarylesters followed by an ammonium acetate participated substitution reaction, forming isoquinolin-1-ones as the major products. Different from most of the known synthetic methods of isoquinolin-1-ones, no metal catalyst was required in the reported reaction. The regioisomers – isoindolin-1-ones were obtained together with isoquinolin-1-ones in a few cases. The intermediate compounds – isochromen-1-ones and isobenzofuran-1-ones were also isolated. The interconversion experiments showed that the regioisomers formed during the Brønsted acid induced intramolecular cyclization of ortho-alkynylarylesters. A natural product – ruprechstyril was prepared in a moderate yield employing the new method