Oracle 18c

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create table table1(col1 varchar2(50));
begin
insert into table1 values('Abc gty xyz');
insert into table1 values('ab/c bpl ?t');
insert into table1 values('qwr .p');
insert into table1 values('titio  iop');
insert into table1 values('TItio  io/');
insert into table1 values('abc');
insert into table1 values('abc     xy');
end;
/
1 rows affected

select col1, case when regexp_like(col1, '^[a-zA-Z][a-zA-Z ]*[a-zA-Z]$') then 1 else 0 end flag 
from table1


COL1
FLAG


Abc gty xyz
1

ab/c bpl ?t
0

qwr .p
0

titio  iop
1

TItio  io/
0

abc
1

abc     xy
1

COL1	FLAG
Abc gty xyz	1
ab/c bpl ?t	0
qwr .p	0
titio iop	1
TItio io/	0
abc	1
abc xy	1