Modular Access to Triarylethylene Units from Arylvinyl MIDA Boronates Using a Regioselective Heck Coupling.

A palladium-catalyzed, silver-mediated Heck coupling between arylvinyl MIDA boronate esters and aryl iodides is disclosed. The reaction provides an efficient and modular access to a range of 1,1-diaryl alkenyl MIDA boronates that can be easily transformed into triarylethylene compounds through a Suzuki coupling.

Streptozotocin treatment of streptozotocin-induced islet cell adenomas in rats.

Hypoglycemic rats bearing insulin-secreting islet-cell adenomas produced by the combined action of streptozotocin and nicotinamide were treated with streptozotocin. Antitumor response was demonstrated by elevation of blood glucose, reduction in plasma and tumor IRI, and histopathologic changes in the beta-cell neoplasm. The rodent tumor model may serve as a predictive system for selection and investigation of mechanisms of action of future antitumor agents to be used in the treatment of malignant insulinoma in man.

Relationship of thyrotropin to exophthalmos-producing substance: formation of an exophthalmos-producing factor by pepsin digestion of mouse pituitary tumor and human thyrotropin preparations.

The present report demonstrates that mouse tumor thyrotropin preprarations have exophthalmogenic activity. In addition it shows that the exophthalmogenic activity of mouse tumor thyrotropin can be increased by partial pepsin digestion, whereas the thyroid stimulating activity of mouse tumor thyrotropin is rapidly destroyed by such treatment. Thus, after 30 min of pepsin digestion, mouse tumor thyrotropin has 130% of its initial exophthalmogenic action but only 10% of its thyroid stimulating activity. Preparations of human thyrotropin are similarly sensitive to partial pepsin digestion, i.e., there is a rapid destruction of thyroid stimulating activity but a very much slower destruction of exophthalmogenic activity. Thus, after 30 min of pepsin digestion, preparations of human thyrotropin retain 80% of their exophthalmogenic activity but only 20-30% of their thyroid stimulating action. Since these results are analogous to those obtained in studies of the partial pepsin digestion of bovine thyrotropin (1), partial pepsin digestion of both purified human and purified mouse tumor thyrotropin preparations should yield an exophthalmogenic fragment of the TSH molecule devoid of thyroid stimulating action.