Photoredox-catalyzed sulfonylation of alkenylcyclobutanols with the insertion of sulfur dioxide through semipinacol rearrangement

Abstract

A photoredox-catalyzed sulfonylation of alkenylcyclobutanols with the insertion of sulfur dioxide through semipinacol rearrangement under visible light irradiation is developed.

Aryldiazonium Salts in Photoredox Catalysis – Recent Trends

“…Alkenyl cyclobutanols containing electron donating & electron withdrawing groups on the aromatic rings under standard reaction conditions affords the desired products in good yields (Scheme 46). [70] …”

“…Alkenyl cyclobutanols containing electron donating & electron withdrawing groups on the aromatic rings under standard reaction conditions affords the desired products in good yields (Scheme 46). [70] The authors proposed the mechanism as shown in Figure 20. [71] At first, the aryl sulfonyl radical, generated from aryldiazonium salt and DABCO • (SO 2 ) 2 , reacts with the olefin of alkenyl cyclobutanol to provide a radical intermediate, which is further oxidized by the photocatalyst to form a cationic intermediate.…”

Recent development and applications of semipinacol rearrangement reactions

“…In 2019, a sulfonylation/semipinacol rearrangement has been established independently by several groups. Among these reactions, various types of reagents, such as ArN 2 BF 4 and (DABCO)$(SO 2 ) 2 , 39 ArSO 2 H, 40 and ArSO 2 Cl, 41 were used to generate arylsulfonyl radicals by means of photoredox-catalysis. Of note, electrochemical conditions have also been applied for the generation of arylsulfonyl radicals from either ArSO 2 NH 2 -NH 2 or PhSO 2 Na, 42,43 which provide mild and convenient protocols for the synthesis of b-sulfonated ketones.…”

Visible‐Light‐Mediated Functionalization of Aryl Diazonium Salts

“…Additionally, 4‐methyl‐2,6‐di‐tert‐butylphenol could only afford the corresponding product in 25% yield, which might be caused by its steric hindrance. In 2019, the Wu group [30b] designed a cascade of radical addition and semipinacol rearrangement. Aryl cyclopentanols gave higher yields (56–91%) than the less strained alkenylcyclopentanol (51%).…”