Continuous Flow Chemistry Synthesis of Spirocyclic Sultams and Isoquinolines through Rhodium‐Catalyzed C−H Activation.

Abstract

In recent years, continuous flow technology have been applied to C−H activation to improve reaction efficiency. Herein, various imines and alkynes have been smoothly applied to continuous flow system. A series of spirocyclic sultams and isoquinolines can be obtained in excellent yields through [3+2] or [4+2] annulation reactions under relatively mild conditions.

H8‐BINOL‐Derived Chiral η6‐Benzene Ligands: New Opportunities for the Ruthenium‐Catalyzed Asymmetric C−H Activation

“…When the ruthenium complex 12 was employed instead of the chiral BenRu II catalyst (S)-7 d, the model reaction of 8 a and 9 a proceeded smoothly to give the product 10 a in 88 % yield with > 99 % ee, suggesting the dechlorinated species of 12 should be a reactive intermediate. Based on the above investigations and previous studies, [19,[21][22][23] a plausible catalytic cycle is proposed (Scheme 7). First, the removal of chloride of (S)-7 d by the silver salt followed by the coordination of DMB anion from…”

“…years only one chiral catalyst -chiral binaphthyl Cp x Rh IIIhas been reported for this transformation by Cramer, [20] giving moderate to good enantioselectivity (75-94 % ee for most cases), despite the emergence of some non-chiral catalysts including Cp*Rh, [19,21] (COD)Ir, [22] and Cp*Co. [23] Application of ruthenium catalysts in this reaction is still unknown. Disappointingly, when the previously developed [2.2]paracyclophane-based chiral BenRu II catalyst (R p )-11 [13] was tested, the product 10 a was obtained in 42 % yield with 15 % ee (Table 1, entry 1).…”

H8‐BINOL‐Derived Chiral η6‐Benzene Ligands: New Opportunities for the Ruthenium‐Catalyzed Asymmetric C−H Activation

“…When the ruthenium complex 12 was employed instead of the chiral BenRu II catalyst (S)-7 d, the model reaction of 8 a and 9 a proceeded smoothly to give the product 10 a in 88 % yield with > 99 % ee, suggesting the dechlorinated species of 12 should be a reactive intermediate. Based on the above investigations and previous studies, [19,[21][22][23] a plausible catalytic cycle is proposed (Scheme 7). First, the removal of chloride of (S)-7 d by the silver salt followed by the coordination of DMB anion from [24] Finally, protonation of VI delivers the chiral product 10 a with the experimentally observed absolute configuration.…”

“…Chemie Zuschrift years only one chiral catalyst -chiral binaphthyl Cp x Rh IIIhas been reported for this transformation by Cramer, [20] giving moderate to good enantioselectivity (75-94 % ee for most cases), despite the emergence of some non-chiral catalysts including Cp*Rh, [19,21] (COD)Ir, [22] and Cp*Co. [23] Application of ruthenium catalysts in this reaction is still unknown. Disappointingly, when the previously developed [2.2]paracyclophane-based chiral BenRu II catalyst (R p )-11 [13] was tested, the product 10 a was obtained in 42 % yield with 15 % ee (Table 1, entry 1).…”

Synthesis of Spiroisoindolinones via Ru(II)-Catalyzed Spiroannulation of N-Acyl Ketimines with Aryl Isocyanates/Isothiocyanates through Aromatic C–H Bond Activation

“…Considering the biological and synthetic importance, chemists are devoting their valuable time to synthesizing spiroisoindolinones in several ways via metal-mediated C–H addition to carbon–carbon multiple bonds and a few through flow chemistry . In 2014, Nishimura and co-workers reported the iridium-catalyzed [3 + 2] annulation of ketimines with internal and terminal alkynes accessing aminoindenes .…”