The 6- chord goes major-dominant and points at 2-. Since 2- usually walks to 5⁷ next, this move sets up a long runway: 6⁷ → 2- → 5⁷ → 1.
hear it in “Crazy” (Patsy Cline) — the 6⁷ everyone knows
Lead-in — how players set it upOften the second chord of a turnaround, right off 1.From 3-, walking the diatonic lane down into 6⁷.Or off 4 — the secondary dominant brightens the descent.Follow — where it usually goes2- heads for 5⁷ like water heads downhill.Stretch it: 2- gets a sus 5 before the cadence.Or go deceptive at the end — 5⁷ to 6-, loop the lane.
The 6⁷'s ♯1 is the spice: touch it on the way to the 2- chord's root.Target tones (in C)C — lean on E (3)A7 — lean on C# (3) · G (b7)Dm7 — lean on F (b3) · C (b7)G7 — lean on B (3) · F (b7)Half-step wiresC → C# · C# → D · E → F · C ↘ B