"As an exception" serves to indicate a deviation from the norm or a one-time circumstance that is different from what is usually expected. There are several synonyms for this phrase that can be used interchangeably, including "in contrast," "with the exception of," "except for," "save for," and "but for." These expressions are all similar in meaning and can be used in various contexts. For instance, you can use "in contrast" to compare two contrasting situations, while "with the exception of" and "except for" emphasize the circumstances that deviate from a larger group. Similarly, "save for" and "but for" signify the exclusions that stand out in a given situation.