Photo-induced spirocyclization of biaryl ynones with ammonium thiocyanate: access to thiocyanate-featured spiro[5,5]trienones

Abstract

Photo-promoted mild tandem 6-exo-trig spirocyclization of biaryl ynones with ammonium thiocyanate has been developed to access thiocyanate-containing spiro[5,5]trienones with good yields and regioselectivity. Meanwhile, other thiocyanate-substituted cycles also could be...

Nitro-Spirocyclization of Biaryl Ynones with tert-Butyl Nitrite: Access to NO2-Substituted Spiro[5,5]trienones

“…1.80 (s, 3H). 13 (22). A yellow solid after purification by flash column chromatography (petroleum ether/ethyl acetate = 5/ 1).…”

“…Consequently, several efficient oxidative/nucleophilic/electrophilic dearomatization and transition-metal or radical-promoted dearomatization processes have been accomplished by many groups so far. − As known, the radical cascade 5- exo -trig and 6- exo -trig spirocyclization of alkynes to access spirocycles have become active areas of research recently. − ,, Among them, many groups respectively developed excellent strategies for the synthesis of spiro­[5,5]­trienones by using biaryl ynones as the starting materials. ,, Recently, our group reported a photoinduced spirocyclization reaction to give SCN-featured spiro­[5,5]­trienones . Despite this advanced work, there is still a fundamental need to find some easy operations and good regioselectivity systems to gain spiro­[5,5]­trienones.…”

“…According to the above mechanistic studies and literature precedent, ,,, biaryl ynones and TBN were selected as model compounds to describe the possible spirocyclization process (Scheme ). First, TBN could smoothly produce NO 2 radical with the assistance of heating or H 2 O.…”

“…19c,g,21 Recently, our group reported a photoinduced spirocyclization reaction to give SCN-featured spiro [5,5]trienones. 22 Despite this advanced work, there is still a fundamental need to find…”

CAN-Promoted Thiolative ipso-Annulation of Unactivated N-Benzyl Acrylamides: Access to SCN/SCF3/SO2Ar Containing Azaspirocycles

“…The solvent was evaporated under reduced pressure, and the residual fraction was purified by silica gel column chromatography using ethyl acetate and hexanes as an eluent to get 5 as a brown liquid, 28.6 mg, 54% yield, R f = 0.3 (hexane:ethyl acetate = 5:5); 1 H NMR (400 MHz, CDCl 3 ) δ 6.91 (dd, J = 10.3, 3.1 Hz, 1H), 6.83 (dd, J = 10.2, 3.1 Hz, 1H), 6.52 (dd,J = 10.3,1.8 Hz,1H),6.46 (dd,J = 10.2,1.8 Hz,1H),3.71 (d,J = 14.4 Hz,1H),3.65 (d,J = 10.6 Hz,1H),3.24 (dd,J = 18.2,12.5 Hz,2H), 1.61 (s, 3H), 1.43 (s, 9H); 13 C{ 1 H} NMR (126 MHz, CDCl 3 ) δ 184. 1,173.8,147.1,146.4,132.9,131.6,131.4,125.2 (q,J = 334.0 Hz),55.3,55.2,50.9,50.3,46.9,27.5,19.4;19 2-(tert-Butyl)-4-methyl-4-(((trifluoromethyl)thio)methyl)-2azaspiro [4.5]decane-3,8-dione (6). Compound 2a (50 mg, 0.14 mmol) was taken in a 10 mL round-bottom flask, dissolved in ethyl acetate (3 mL), and cooled to 0 °C under a H 2 atmosphere.…”