How to convert the phrase into sentence case, disregard the UPPERCASE words

I want to convert all the text to "Sentence case", but I need the UPPERCASE words to remain UPPERCASE. I would manually write it if the file wasn't ~50.000 rows.

A string could start with letters, numbers or symbols.

These are some examples of what I want:

A	B
247 Metal Bridge Handle	247 Metal bridge handle
ADRIANO Back Cushion	ADRIANO back cushion
Quartz And Crystal Quartz 60 Mm	Quartz and crystal quartz 60 mm
* Fully Integrated Dishwasher By Client*	* Fully integrated dishwasher by client*
_____Lacquered Woods _____	_____Lacquered woods _____
Base unit 2 doors + 2 shelves [L_10CUC]	Base unit 2 doors + 2 shelves [L_10CUC]
Hood HILIGHT X - Stainless steel	Hood HILIGHT X - stainless steel

I tried some suggested formulas and VBAs but each one give some errors:

=MID(A1,MATCH(65,CODE(MID(A1,ROW(INDIRECT("1:"&LEN(A1))),1)),1)+1,1)

it will find my first letter (then I can easily search for what's on its left and on its right, and make it lowercase) but sometimes it fails: in B3 I was expecting "A".

A	B
247 Metal Bridge Handle	M
* Fully Integrated Dishwasher By Client*	F
ADRIANO Back Cushion	N

I also can get my first letter with some VBA but if i want to discard symbols I have to type each one:

Function FirstChar(Stringa As String)
Application.Volatile
Dim sStr As String
Dim i As Long

For i = 1 To Len(Stringa)
If Not IsNumeric(Mid(Stringa, i, 1)) Then
If Mid(Stringa, i, 1) <> " " And Mid(Stringa, i, 1) <> "*" Then
FirstChar = Mid(Stringa, i, 1)
Exit Function
End If
End If
Next i

FirstChar = CVErr(xlErrNA)

End Function

A	B
247 Metal Bridge Handle	M
* Fully Integrated Dishwasher By Client*	F
___ADRIANO Back Cushion	_

Anyway is missing the way to keep the UPPERCASE words.

Solution

Basic UDF approach:

Function SentenceCase(ByVal s As String)
    Dim c As String, i As Long, rv As String, first As Boolean, cap As Boolean, capSeq As Boolean
    s = s & " " 'fudge to simplify checking on next character without running off the end of the string
    first = True
    For i = 1 To Len(s) - 1
        c = Mid(s, i, 1)
        cap = c Like "[A-Z]" 'is this a capital?
        If Not cap Then
            rv = rv & c 'pass non-cap
        Else
            If Not IgnoreCaps(s, i) Then
                rv = rv & IIf(first, c, LCase(c)) 'lower-case if not first capital
            Else
                rv = rv & c 'pass through
            End If
            first = False 'not the first capital
        End If
    Next i
    SentenceCase = rv
End Function

'Is letter at position `i` in string `s` preceded by a capital letter,
'   or followed by a capital letter or underscore?
Function IgnoreCaps(s As String, i As Long) As Boolean
    IgnoreCaps = Mid(s, i + 1, 1) Like "[A-Z_]"
    If i > 1 And Not IgnoreCaps Then
        IgnoreCaps = Mid(s, i - 1, 1) Like "[A-Z]"
    End If
End Function

Might need teaks in IgnoreCaps for other use cases...