There are several synonyms for the phrase "be going to do something". Some of them include "intend to", "plan to", "aim to", "propose to", "have designs on", "aspire to" and "have in mind". Each of these synonyms carries a slightly different connotation and may be more appropriate in certain contexts. For example, "intend to" implies a strong determination to do something, while "plan to" suggests a well thought-out strategy. "Aim to" suggests a desire to achieve a particular goal, while "propose to" implies a formal intention. Understanding the nuances of these synonyms can help writers choose the most appropriate language for their intended meaning.