Ultegra CS-R8000 11-speed is available in 14-28. (many online stores don't stock these. A little hard to find.)

It's a straight block from 14 through 21:
14 15 16 17 18 19 20 21 23 25 28


I use this for my fast-for-me group rides, since it has close shifts from 16 through 25 mph. The downside is having to shift 4 or 5 cogs when shifting the front rings (but that's fast and easy with Di2). And spinning out at 30 mph.

I'll also combine it with the 5 large cogs from an 11-32 if there's steep hills:
14 15 16 17 18 19 20 22 25 28 32

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The 14-28 with 34/50 chainrings. 36/52 would be about 1/2 shift higher gearing (a 4% difference). At 100 rpm, 52-17 is 24.0 mph, 50-17 is 23.1 mph.

Chart from Mike Sherman's Gear Calculator. Here's the link to this setup, with a 50 vs 52 comparison: 14-28 and 36/50/52