DS has just turned 4 and is an only child. He's gone to nursery from age 1 and is in pre-school, so is well used to being around other children. He was early with speech and is very articulate. He's always been quite bossy and controlling, particularly when playing games (wants everything done his way, gets worked up when others want to do different things). DH and I assumed it was just him being a young child, but his pre-school teachers have started to comment on it and it was even in his mid-year report (along the lines of "needs to be encouraged to listen to his friends' ideas"). So it seems to be beyond the norm.
It seems to have started to alienate his little friends and he often comes home saying x doesn't want to play with him any more. We have tried talking to him about taking turns with ideas, practising this at home, but it doesn't seem to be helping.
I don't want him to end up as a dictator with no friends 
Would be really grateful for any suggestions.