Ru (II)‐Catalyzed Coupling‐Cyclization of Sulfoximines with alpha‐Carbonyl Sulfoxonium Ylides as an Approach to 1,2‐Benzothiazines

Abstract

A Ru(II)-catalyzed approach for the rapid assembly of 1,2-benzothiazines has been developed to enable the coupling-cyclization of aryl Csp 2 ÀH bonds with a-carbonyl sulfoxonium ylides via Csp 2 ÀH activation process. The present method could be further applied to the construction of the 4-substituted 1,2benzothiazine skeletons.

Ruthenium Catalyzed C−H Acylmethylation of N‐Arylphthalazine‐1,4‐diones with α‐Carbonyl Sulfoxonium Ylides: Highway to Diversely Functionalized Phthalazino‐fused Cinnolines

“…On the basis of our preliminary mechanistic results and literature precedents, a plausible mechanism for the o ‐acylmethylation and the two disclosed cyclizations are proposed (Scheme ). The reaction is believed to be initiated by the formation of active monomeric Ru II catalyst, {[RuX 2 ( p ‐cymene)]; X=PF 6 and/or Cl} by the dissociation of dimeric [RuX 2 ( p ‐cymene)] 2 with KPF 6 .…”

“…On the basis of our preliminary mechanistic resultsa nd literature precedents, [14,15,19,20] ap lausible mechanism for the oacylmethylation and the two disclosed cyclizationsa re proposed (Scheme 9). The reactioni sb elieved to be initiated by the formation of active monomeric Ru II catalyst, {[RuX 2 (pcymene)];X = PF 6 and/or Cl} by the dissociation of dimeric [RuX 2 (p-cymene)] 2 with KPF 6 .C yclometalation of this Ru II catalyst with 1a generates the five-membered ruthenacyclic intermediate A via CÀHa ctivation, which upon coordinationw ith sulfoxonium ylide (2)and subsequent eliminationofD MSO furnishes ar uthenium a-oxo carbene species B.T hereafter,m igratory insertion of the activated carbenei nto Ru-aryl bond gives as ix-memberedr uthenacyclic intermediate C,w hich upon protonolysis of the RuÀNa nd RuÀCb onds produces o-acylmethylated product 3,along with the regeneration of the active catalyst.…”

“…LR (1 (Table 2, entries [14][15]. Albeitn of urther change was observed by using 3equiv of BF 3 ·OEt 2 (Table 2, entry 16).…”

“…disclosed Ru II ‐catalyzed coupling‐cyclization of S ‐arylsulfoximines with α‐carbonyl sulfoxonium ylides to obtain 1,2‐benzothiazines. (Scheme c) . Maulide et al.…”

“…(Scheme 1c). [14] Maulidee tal. presentedt he cross-olefination of diazo compounds with sulfoxonium ylides under Ru-catalyzed conditiont oa fford Z-olefins (Scheme 1d).…”