We then applied the optimal conditions (Table , entry 7) to a number of TBS-enol ethers (Scheme 2a). With electron-donating groups at the para position of the aryl group at R 1 , the corresponding carbamates 5b and 5c were obtained with high efficiency (80 and 60% yields, respectively). Also, F-substituted silyl enol ether 2d gave 5d in 52% yield.Thiophene 1e gave the corresponding carbamate 5e in a good yield of 64%. The reaction was found to be sensitive to steric effects on R 2 . Thus, with an ethyl group at R 2 , 5f was obtained in a lower yield (49%). For aliphatic tert-butyldimethylsilyl enol ethers 1g and 1h, yields of 51 and 46%, respectively, were obtained. To assess the generality of the reaction, we tested different secondary amines to form the carbamate. Symmetrically and unsymmetrically substituted dialkyl amines reacted smoothly to give good yields (5i-5k, 60-80%). Moreover, pyrrolidine substituted carbamate 5l was also obtained under the reaction conditions in 58% yield. However, carbamates derived from primary amines gave a mixture of unidentified products (not shown), which represents a major limitation of this approach. Significantly, this umpolung strategy is not limited to silyl enol ethers, but could be extended to the use of 1,3-dicarbonyl compounds. A b-ketoester 6a reacted smoothly under the same conditions to give 7a in 82% yield. 1,3-Dicarbonyl compound 6b reacted with carbamate 4 to give 7b in good yield (56%). The less nucleophilic b-amidoester 6c and malonate 6d gave carbamoyl derivatives 7c and 7d in good yields (68 and 78%, respectively).