Synthesis of Macrocyclic Lactones<i>via</i>Ring Transformation of 4-(<i>ω</i>-Hydroxyalkyl)-1,3-oxazol-5(4<i>H</i>)-ones
作者:Stephan P. Fritschi、Anthony Linden、Heinz Heimgartner
DOI:10.1002/hlca.201600023
日期:2016.7
α‐benzamido‐α‐benzyl lactones 23 of various ring size was achieved either via ‘direct amide cyclization’ by treatment of 2‐benzamido‐2‐benzyl‐ω‐hydroxy‐N,N‐dimethylalkanamides 21 in toluene at 90 – 110° with HCl gas or by ‘ring transformation’ of 4‐benzyl‐4‐(ω‐hydroxyalkyl)‐2‐phenyl‐1,3‐oxazol‐5(4H)‐ones under the same conditions. The precursors were obtained by C‐alkylations of 4‐benzyl‐2‐phenyl‐1,3‐oxazol‐5(4H)‐one
各种环大小的α-苯甲酰胺基-α-苄基内酯23的合成可通过在90°C的甲苯中处理2-苯甲酰胺基-2-苄基-ω-羟基N,N-二甲基烷酰胺21的“直接酰胺环化”来实现–在相同条件下用HCl气体或通过4-苄基-4-(ω-羟烷基)-2-苯基-1,3-恶唑-5(4 H)-1的“环转化”至110° 。前体是通过4-苄基-2-苯基-1,3-恶唑-5(4 H)-one(15)与THP-或TBDMS保护的ω的C-烷基化获得的羟烷基碘化物 用Me 2 NH处理使THP保护的恶唑酮开环,然后使OH基脱保护,得到二酰胺21;而用TBAF对TBDMS系列的恶唑酮25脱保护,然后用HCl气体处理,得到相应的内酯23。一锅反应。