One-pot chemo/regio/stereoselective generation of a library of functionalized spiro-oxindoles/pyrrolizines/pyrrolidines from α-aroylidineketene dithioacetals
Cyclocondensation of 2-lithiomethylthiazoles and 2-lithiomethylthiazoline with α-oxoketene dithioacetals: synthesis of substituted and annelated thiazolo- and dihydrothiazolo[3,2-a]pyridinium compounds
The oxoketene dithioacetals 1 undergo regioselective 1,2-addition with 2-lithiomethyl-4-methylthiazole (2a) and 2-lithiomethylthiazoline (3) to afford the carbinol acetals 4 which on borontrifluoride etherate assisted cyclization yield the corresponding substituted and annelated 3-methyl-5- methylthiothiazolo[3,2-a.] pyridinium tetrafluoroborates (5a-g, 8a,b,10,12) and the dihydro derivatives (23-25)
2-c]thiazol]-2-one have been achieved through1,3-dipolarcycloaddition. Intermediate azomethine ylides generated in situ from α-amino acids and acenaphthylene-1,2-dione react with α-aroylidine ketenedithioacetal (AKDTA) derivatives to give the target product in excellent yield underultrasoundirradiation. Further, spiro-S,S-acetals are converted to spiro-2H-pyranones by a one-pot cyclization strategy.
新型螺[[-1,3'-吡咯烷] -2-一和螺[ac-1,5'-吡咯并[1,2- c ]噻唑] -2-的文库的立体/区域/化学选择性合成一种是通过1,3-偶极环加成反应实现的。由α-氨基酸和1,2-二酮原位产生的中间体甲亚胺基亚烷基与α-芳基亚乙基酮二硫缩醛(AKDTA)衍生物反应,在超声波照射下以优异的收率得到目标产物。此外,通过一锅环化策略将螺-S,S-乙缩醛转化为螺-2 H-吡喃酮。
One-pot chemo/regio/stereoselective generation of a library of functionalized spiro-oxindoles/pyrrolizines/pyrrolidines from α-aroylidineketene dithioacetals