As we all know 正确
all / both / each等词的位置1.系动词之后 2 行为动词之前 3.第一谓语之后.如
1 We are all students
2.We all worked hard
3.We have all known the secret / We will all help him with his study.
再者,你的表述中as是引导非限制性定语从句,as要在从句中作成分,要么主语,要么宾语,所以As we all know 中as做了know 的宾语； 而as all we know ,是all作know的宾语吗?那么as就不作成分了,因此 不对
如,As we all know,he is a clever boy.
As is known to all ,he is a clever boy.