That said, about your coding-to-vision thing: it sounds like he's just unable to dedicate the time to define the UX in detail. That's understandable, as a manager it's essential to delegate.

However, defining the product (scope, features, UX, …) is a core part of the business, and needs involvement from management (business strategy), customers/salespeople (market fit: have you talked to your customers yet?), designers and coders.

So, maybe do as much as you can for him (on paper or whatever), and when you're ready present the screens to him in a quick 10 minutes briefing.

If he still feels like you're wasting everybody's time, make him a business case based on past experience; ie. "Defining the UI would've cost us _this_ much in time, charging ahead has cost us _this_ much in time: we're losing money and wasting time."

If he still won't see the light, it's pretty much doomed.

Honestly, this doesn't sound like that kind of guy. From what you described, he's "all hat and no cattle" (as they say in Texas).