Looking for articles and or theories that explore the idea that morphology and syntax are not separate but operate on the same principles; for example, that the sentence is just an extended morphological word (using those terms generally, external of their various theoretical use).
First, I'll point to a previous question on this SE, What meaningful distinction is there between morphology and syntax?. I'll just present one line of approach.
A seminal article is Mark Baker's 1985 The Mirror Principle and morphosyntactic explanation, wherein he defines the Mirror Principle as follows:
Subsequently, Distributed Morphology (DM) was developed by Morris Halle & Alec Marantz and colleagues. I quote from their 1993 paper, Distributed Morphology and the pieces of inflection (pdf):
Two points: first, it is in a sense the opposite of what you mention in your question, in that a morphologically derived word is claimed to have internal syntactic structure. Second, DM is not pure syntax (hence the "Distributed" label): it does have a number of post-syntactic operations that derives morphological generalizations such as syncretism (where different morphosyntactic feature bundles like first person singular and second person singular are realized by the same morpheme).
There are a number of resources for DM: