Palladium-Catalyzed Three-Component Dearomatization/Sulfonylation Cascade

Abstract

The diastereoselective synthesis of sulfonylated indolines is reported. A palladium-catalyzed dearomative sulfination of (aza)­indole-tethered aryl iodides generates reactive benzylic sulfinates. These intermediates react with electrophiles in a one-pot, two-step process to generate sulfonylated products in good yields and excellent diastereoselectivity. This three-component sequence demonstrates good scalability and can be applied toward the synthesis of sulfonamides. Additionally, further derivatizations of aryl iodide containing products furnish spiro- and alkynylated indoline products.

Ring-Opening of Donor-Acceptor Cyclopropane Diester for the Synthesis of Oxime Esters and 2,3-Dihydroazete Ester

“…For the tosyl elimination step, the use of organic bases such as DBU, DMAP, and TBAF did not yield the product (Table 1, entries 12-14). Furthermore, the inorganic bases such as K2CO3, Na2CO3, and NaH gave lower yields of the product or other unpredictable side products (Table 1, entries [15][16][17]. Subsequently, changing the solvent acetonitrile instead of THF, gave a 20% yield of the product (Table 1, entry 19), whereas DMF at 80 °C failed to give the product (Table 1, entry 20).…”

“…14 Furthermore, traditional methods often require a similar carbonyl ester substrate and an amine group to synthesize target oxime esters (Scheme 1 B, left). 15 In contrast, we have developed an approach for the construction of oxime esters by using strained ring systems as one of the precursors along with hydroxylamine derivatives (Scheme 1 B, right). The use of strained ring systems such as DACs for the synthesis of oxime esters has not been reported yet.…”

Recent advances in palladium-catalyzed sulfonylation via SO2 insertion

“…In the next year, Lautens's group depicted a palladium-catalyzed three-component sulfination process from aryl iodides to diastereoselectively prepare polycyclic sulfonylated products (Scheme 23). 32 Although there have been extensive studies reporting two-component processes to install a new C-C bond or C-heteroatom bond, such as boron, phosphorus and silicon atoms onto indolines through the domino Heck/dearomatization cascade, the development of an efficient three-component process for constructing a C-S bond has not been reported. This reaction used this strategy to realize the formation of a C-S bond via palladium-catalyzed indole dearomatization, expanding the scope of functionalized indoline products.…”

Palladium-catalyzed domino cyclization/direct functionalization involving the insertion of SO2

“…Among them, transition metal-catalyzed SO 2 insertion reactions generally contain two steps involving sulfinates as key intermediates (Scheme 1a). 15 To avoid the complicated operation of a two-step pathway, Toste, Smith, Willis, Wu, Tu and other groups have developed a one-step pathway to sulfonyl compounds via catalytic cross-coupling of various organometallic reagents with SO 2 surrogates and electrophiles (Scheme 1b). 16 Very recently, Jiang and co-workers pioneered a multicomponent reductive cross-coupling strategy to construct sulfones through a combination of two electrophiles (aryl halides and alkyl halides) with a SO 2 surrogate (Scheme 1c).…”