The phrase "astounding as it" is not complete and therefore not correct in written English.
It can be used in a context where you are comparing something to another thing that is astounding, but it needs to be followed by a noun or clause to make sense.
Example: "The performance was astounding as it left the audience in awe."
Alternatives: "incredible as it" or "remarkable as it".
The extent to which the JOBS Act allows a company to operate in the dark is as astounding as it is depressing.
The Birth of a Nation is every bit as astounding as it's cracked up to be, and for good reasons as well as bad.
As astounding as it sounds, no agency or department of government keeps data on young adults with chronic conditions.
The stink coming from the air holes in the lid is astounding as it is, but wait until next month — we are about to take a shit in the jar.
The third option was most astounding as it meant trans-differentiation to a nonmalignant phenotype.
Astounding as it may seem, the fact is that President Roosevelt's "one-third of a nation" was a considerable understatement; over two-thirds of us then lived below the poverty line, as is shown by the tables that follow.
But get it right and the effects can be astounding, as this unique exhibition reveals.
Much should be and has been made of Mr. Simkin's silky virtuosity: the speed with which he whips through high, turning leaps is astounding, as is his ease in landing.
The sheer complexity of the game is astounding: as well as constructing impenetrable prison walls from a range of hardy materials, you've got to think about plumbing in showers, installing metal detectors (to stop families smuggling stuff in on visits), providing facilities to let the guards rest, deciding how to punish inmates if they violate rules, and so on.
The gowns and jewels were astounding, as was the amount of "work" done to the women wearing them.
The resemblance between real-life Saint Laurent and Niney are astounding, as is the way the Frenchman so completely embodies the essence of the designer and his struggles with substance abuse, relationships and his collections.
