Mandal Pratap Kumar, Chakrawarti Rahul, Katukojvala Sreenivas
Department of Chemistry, Indian Institute of Science Education & Research Bhopal, Bhopal, Madhya Pradesh 462066, India.
Org Lett. 2024 Apr 26;26(16):3463-3468. doi: 10.1021/acs.orglett.4c01033. Epub 2024 Apr 16.
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-2-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-2-thiopyrans are novel precursors for unstudied 2-thiopyran-2-ones and 4-thiopyran-4-ones. The 4-thiopyran-4-ones were obtained via a novel O/EtN-mediated oxidative deformylation. This methodology was applied to the short synthesis of structurally complex pyrimidine-fused 2-thiopyran via cascade Schmidt, Ritter, and intramolecular cyclization reactions.
在此，我们报道了一种新型的铑（II）/钪（III）催化的重氮烯醛与α-巯基酮之间的[3+3]环化反应，用于直接合成4-甲酰基-2-硫代吡喃。该反应通过由高亲电性铑-烯基卡宾衍生的质子化硫鎓叶立德进行，随后进行区域选择性分子内羟醛缩合反应。进一步的研究表明，4-甲酰基-2-硫代吡喃是未被研究的2-硫代吡喃-2-酮和4-硫代吡喃-4-酮的新型前体。4-硫代吡喃-4-酮是通过一种新型的O/EtN介导的氧化脱甲酰基反应得到的。该方法被应用于通过级联施密特反应、 Ritter反应和分子内环化反应，简洁地合成结构复杂的嘧啶稠合2-硫代吡喃。
