Exploiting an intramolecular Diels-Alder cyclization/dehydro-aromatization sequence for the total syntheses of ellipticines and calothrixin B.

The tetracyclic and pentacyclic skeletons of pyrido and quinolinocarbazole alkaloids have been synthesized via a unified strategy. The prominent key step involved a Diels-Alder intramolecular cyclization/dehydro-aromatization sequence. From these carbazole-lactam cores, linear syntheses have been developed for ellipticines and calothrixin B.

Airflow of the Two-Port Velopharyngeal Closure: Study Using Computational Fluid Dynamics.

Posterior pharyngeal flap palatoplasty is used to restore the function of velopharyngeal (VP) closure, after which 2 ports remain between the nasal and oral cavity. The authors hypothesized that the airflow dynamics of the upper airway is different in PPF patients compared to health subjects, who only has 1 movable port. Twenty adults who have multislice spiral computed tomography scan were included in this study.