Palladium-Mediated Cyclization on Carbohydrate Templates. 1. Synthesis of Enantiopure Bicyclic Compounds
摘要:
The bromo unsaturated carbohydrates 30 and 9 were prepared from ethyl 4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranoside (1a) and (7) by deacetylation followed by monosilylation with TBDMSCl and then alkylation with BrCH2CBr=CH2. The three analogues 6 and 10 were obtained using the same methodology after inversion at C-4 via a Mitsunobu reaction. The N- and C-analogues 4b and 5 were prepared by palladium alkylation of the carbonate 2d with TsNHCH(2)CBr=CH2 and (CO(2)Me)(2)CHCH2CBr=CH2, respectively. Treatment of the unsaturated carbohydrates 3a and 9 with a catalytic amount of Pd(OAc)(2)/PPh(3) in CH3CN/H2O in the presence of Bu(4)NHSO(4) and NEt(3) afforded the bicyclic compound 14a. The N- and C-analogues 14b and 14c were obtained using the same conditions and starting, respectively, from 4b and 5. On the other hand, treatment of the three derivatives 6 and 10 under these conditions gave the furanic structure 15. In the case of compound 30, performing the reaction in the presence of sodium formate yielded the bicyclic 2-deoxy carbohydrate 17.
Palladium-Mediated Cyclization on Carbohydrate Templates. 1. Synthesis of Enantiopure Bicyclic Compounds
摘要:
The bromo unsaturated carbohydrates 30 and 9 were prepared from ethyl 4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranoside (1a) and (7) by deacetylation followed by monosilylation with TBDMSCl and then alkylation with BrCH2CBr=CH2. The three analogues 6 and 10 were obtained using the same methodology after inversion at C-4 via a Mitsunobu reaction. The N- and C-analogues 4b and 5 were prepared by palladium alkylation of the carbonate 2d with TsNHCH(2)CBr=CH2 and (CO(2)Me)(2)CHCH2CBr=CH2, respectively. Treatment of the unsaturated carbohydrates 3a and 9 with a catalytic amount of Pd(OAc)(2)/PPh(3) in CH3CN/H2O in the presence of Bu(4)NHSO(4) and NEt(3) afforded the bicyclic compound 14a. The N- and C-analogues 14b and 14c were obtained using the same conditions and starting, respectively, from 4b and 5. On the other hand, treatment of the three derivatives 6 and 10 under these conditions gave the furanic structure 15. In the case of compound 30, performing the reaction in the presence of sodium formate yielded the bicyclic 2-deoxy carbohydrate 17.
The bromo unsaturated carbohydrates 30 and 9 were prepared from ethyl 4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranoside (1a) and (7) by deacetylation followed by monosilylation with TBDMSCl and then alkylation with BrCH2CBr=CH2. The three analogues 6 and 10 were obtained using the same methodology after inversion at C-4 via a Mitsunobu reaction. The N- and C-analogues 4b and 5 were prepared by palladium alkylation of the carbonate 2d with TsNHCH(2)CBr=CH2 and (CO(2)Me)(2)CHCH2CBr=CH2, respectively. Treatment of the unsaturated carbohydrates 3a and 9 with a catalytic amount of Pd(OAc)(2)/PPh(3) in CH3CN/H2O in the presence of Bu(4)NHSO(4) and NEt(3) afforded the bicyclic compound 14a. The N- and C-analogues 14b and 14c were obtained using the same conditions and starting, respectively, from 4b and 5. On the other hand, treatment of the three derivatives 6 and 10 under these conditions gave the furanic structure 15. In the case of compound 30, performing the reaction in the presence of sodium formate yielded the bicyclic 2-deoxy carbohydrate 17.