Moses Kann belonged to one of the most influential Frankfurt families . They were involved in numerous longdrawnout and bitter feuds, including the DrachKann disputes and the KannKulp disputes, which were carried on to maintain their supremacy within the Judengasse.
Moses Kann and his brother Beer Löw Isaac zur Kann were court Jews in the service of the Grand Duke of HesseDarmstadt and, after 1743, of the Elector of Mainz. They were by far the wealthiest Jews in Frankfurt, their fortune at their peak exceeding half a million guilders.
Unlike his brother, Moses had a reputation not just as a businessman but also as a great Talmudic expert. The Frankfurt rabbi and historian Markus Horovitz described him as "the greatest scholar and most respected man in our Community". The political powerstruggle within the community was directed only at his brother, and not at him, although he was also affected by it.
Moses Kann worked as a teacher in the zur Klause yeshiva, where he taught the Talmud to Jewish students. Zur Klause had been endowed by Manasse Darmstädter in 1685; Moses Kann and his family continued to support it financially. His first wife, the daughter of the imperial court factor in Vienna, Samson Wertheimer, died prematurely. In her memory, the Samson Wertheimer Trust was established, which funded the house zur Klause until its demolition in 1883.
Moses Kann was also chief rabbi of the Grand Duchy of HesseDarmstadt.
By the time of his death in December 1761 he, like his brother, had lost his entire fortune, and had practically nothing to leave to his son and daughter.