Chicken with Shallots, Prunes, and Armagnac

Boil prunes with 1/3 cup Armagnac in small saucepan until almost all liquid is absorbed, about 3 minutes. Cover and set aside. Heat oil in heavy large skillet over medium-high heat. Sprinkle chicken with salt and pepper. Add to skillet, skin side down; cook until browned, about 5 minutes per side. Transfer to plate. Pour off all but 2 tablespoons drippings. Add shallots; cook until browned in spots, about 5 minutes. Add remaining 1/3 cup Armagnac; boil 30 seconds, scraping up browned bits. Add broth, prunes, and thyme sprigs; bring to boil. Add chicken in single layer, skin side up, and any accumulated juices. Cover, reduce heat to medium, and simmer until chicken is cooked through, about 17 minutes. Transfer chicken to plate. Stir vinegar into sauce; simmer until thickened, 3 minutes. Remove thyme sprigs. Season with salt and pepper. Pour sauce over chicken. Sprinkle with chopped thyme.