I have noted before that the Torah as a whole follows a pattern of narrative, poetry, epilogue. Genesis follows this pattern. Exo-Num follows this pattern. And Deuteronomy follows this pattern. Before each of the key poems the Hebrew text uses the word “aharith” (Gen 49:1, Num 24:14, and Deut 31:29). Thus Deut 1-31 has narrative, Deut 32:1-47 is poetry, and Deut 32:48-52 is the epilogue. This is a very fitting ending for Deuteronomy. But then Deuteronomy adds another poem (Deut 33) and epilogue (Deut 34) written from a later perspective (after prophecy has ceased because it says, “there has not arisen a prophet since in Israel like Moses, whom YHWH knew face to face…” (Deut 34:10ff). The other big textual clue to a later date for this section is the phrase “but no one knows the place of his burial to this day” (Deut 34:6). To what day? Much later.
I have written about some of the themes and agendas of this additional poem and epilogue in my post The Way of Wisdom: The Canon and Cessation. As I said there, the extra poem and epilogue are Scripture (fully the word of God as well as of this editor). And one of the things that Sailhamer notes in his book cited there, if I remember correctly, is that the additional poem reflects the poem of Gen 49 but you can see its distinctive emphases by comparing the two poems. The one big difference is the additional emphasis on the tribe of Levi in this poem in Deuteronomy because the wisdom teachers of Scripture were Levites.
So the big picture of the structure is [prologue,] narrative, poetry, epilogue, poetry, epilogue. It is also worth noting that the narrative is a series of speeches. The first speech is Deut 1:6-4:40, the second is Deut 5:1-28:68, the third is Deut 29:1-30:20, and the fourth is Deut 31:1-8. Deut 1:1-5 are introducing the speeches and the first speech in particular, Deut 5:1a is a brief introduction to the second speech, Deut 29:1-2a is a brief introduction to the third speech, and a fourth speech is introduced in Deut 31:1-2a, with a brief intro in Deut 31:7 to the rest of the speech. The effect of these introductions is to put the speeches in a narrative context much like the same for the laws back in Leviticus. Deut 31:9 then continues the narrative where the emphasis is on passing on Deuteronomy to future generations (a concern of the editor too). And the narrative transitions to introducing the first poem-song.
The reason I said above that the structure is best described as prologue, narrative, poetry, epilogue, poetry, epilogue is because Deut 1:1-5 can be understood as a prologue or preamble to the book. This is a more elaborate form of the narrative, poetry, epilogue pattern in Torah that we saw in some books in Genesis. Calling it a prologue or preamble actually opens the door for beginning to note that the structure of the book actually resembles a Hittite covenant-treaty format. Thus the preamble of the treaty is Deut 1:1-5, the historical prologue is the first speech (Deut 1:6-4:40 plus the narrative that follows Deut 4:41-49), the covenant stipulations (Deut 5:1-26:19) and sanctions (Deut 27:1-30:20) are laid out in the second and third speeches. And the rest of the book also has elements easily identified with normal parts of such a treaty. We saw before that Leviticus 18 and more loosely the whole Holiness Code of Leviticus also follow this pattern. Looking at Deuteronomy this way is the approach of Meredith Kline and is a very helpful observation.
Noting the prominence of speeches or sermons in the book highlights the Hebrew title based on the opening words of Deuteronomy, “These are the words.”