Facile cyclization of sodium aminodiboranate to construct a boron-nitrogen-hydrogen ring.

A facile and efficient cyclization of sodium aminodiboranate to construct a boron-nitrogen-hydrogen ring is presented. This new strategy can be developed into a general method to prepare aminodiborane and its derivatives. Theoretical calculations show that a one-step cyclization mechanism is favored, where the dihydrogen bond plays an important role.

Assessing the risk of multiple gestation in gonadotropin intrauterine insemination cycles.

Objective: The purpose of this study was to analyze factors for their ability to predict multiple gestation in women who undergo controlled ovarian hyperstimulation with gonadotropins (follicle-stimulating hormone/human menopausal gonadotropin) and intrauterine insemination.

Study Design: This was a retrospective analysis of the clinical and laboratory variables that are associated with multiple gestation. Data for 6 variables in 678 cycles of gonadotropin/intrauterine insemination between 1990 and 1999 were analyzed with survival analysis, Cox regression analysis, and multiple logistic regression.