[3+3] Annulation of Diazoenals and α-Mercapto Ketones via Protic Sulfonium Ylides: Direct Synthesis of 2<i>H</i>-Thiopyrans, Innovative Progenitors for Unstudied 2<i>H</i>-Thiopyran-2-ones and 4<i>H</i>-Thiopyran-4-ones
作者:Pratap Kumar Mandal、Rahul Chakrawarti、Sreenivas Katukojvala
DOI:10.1021/acs.orglett.4c01033
日期:2024.4.26
Herein, we report a new Rh(II)/Sc(III)-catalyzed [3+3] annulation between diazoenals and α-mercapto ketones for the direct synthesis of 4-formyl-2H-thiopyrans. The reaction proceeds via protic sulfonium ylides derived from highly electrophilic Rh-enalcarbenoids, followed by regioselective intramolecular aldol condensation. Further studies revealed that 4-formyl-2H-thiopyrans are novel precursors for unstudied
在此,我们报道了一种新的Rh(II)/Sc(III)催化的重氮烯醛和α-巯基酮之间的[3+3]环化反应,用于直接合成4-甲酰基-2H-噻喃。该反应通过由高亲电性铑烯醛类化合物衍生的质子锍叶立德进行,然后进行区域选择性分子内羟醛缩合。进一步的研究表明,4-甲酰基-2 H-噻喃是未研究的2 H-噻喃-2-酮和4 H-噻喃-4-酮的新型前体。 4 H-噻喃-4-酮是通过新型O 2 /Et 3 N介导的氧化去甲酰化获得的。该方法通过级联 Schmidt、Ritter 和分子内环化反应,应用于结构复杂的嘧啶稠合 2 H-噻喃的短合成。