No all jars of sauce have syns and can be really high in syns - if you want a syn free one you will need to make it yourself. There are lots of recipes in the recipe sub-forum and it's really easy to do.
My basic tomato sauce recipe is so simple and you can do it while your pasta is cooking. In a frying pan, add a can of chopped tomatoes, a splash of worcestershire sauce, a splash of soy sauce, a large pinch of granulated sweetener, a veg or chicken oxo cube, and a sprinkle of schwartz garlic italian seasoning. Stir it all together, bring it to the boil then reduce the heat and simmer over a low heat until your pasta is ready.
it is really versatile as you can add chilli for more punch or philly cheese for a creamy sauce.