Heat oil in heavy large skillet over medium heat. Add onion and pepper and saute until tender, about 5 minutes. Add garlic and saute a bit more.., oregano and dried red pepper and stir 1 minute. Add stewed tomatoes, diced tomatoes,and lemon juice and simmer until sauce thickens slightly and artichokes are tender, about 30 minutes.(Can be made 1 day ahead. Cover and refrigerate.)

Cook spaghetti in large pot of boiling salted water until tender but still firm to bite. Drain. Meanwhile, bring sauce to a simmer. Stir in shrimp and simmer until just cooked through, about 5 minutes. Season to taste with salt and pepper. Add spaghetti to sauce and toss to coat. Transfer to large bowl. Sprinkle with additional chopped fresh basiL