A Mild Synthesis of Vinyl Halides and gem‐Dihalides Using Triphenyl Phosphite—Halogen‐Based Reagents.

Abstract

Halogenation O 0235 A Mild Synthesis of Vinyl Halides and gem-Dihalides Using Triphenyl Phosphite-Halogen-Based Reagents. -The reaction of enolizable ketones efficiently provides vinyl halides, whereas starting from non-enolizable ketones and aldehydes gem-dihalides are obtained. -(SPAGGIARI, A.; VACCARI, D.; DAVOLI, P.; TORRE, G.; PRATI*, F.; J. Org. Chem. 72 (2007) 6, 2216-2219; Dip. Chim., Univ. Modena, I-41100 Modena, Italy; Eng.) -Jannicke 30-038

Cyclic Hypervalent Iodine Reagents for Azidation: Safer Reagents and Photoredox-Catalyzed Ring Expansion

“…(1-(3,4-Dihydronaphthalen-1-yl)cyclobutoxy)trimethylsilane (4s). Following a reported procedure, 40 Br 2 (0.60 mL, 12 mmol, 1.25 equiv) was added dropwise to a solution of triphenyl phosphite (2.7 mL, 10 mmol, 1.1 equiv) in anhydrous dichloromethane (31.1 mL) maintained at −60 °C under Ar. A solution of Et 3 N (1.7 mL, 13 mmol, 1.35 equiv) and 3,4-dihydronaphthalen-1(2H)-one (26) (1.2 mL, 9.3 mmol, 1.0 equiv) in DCM (5 mL) was then added, and the resulting mixture was stirred for 18 h, while allowing it to warm to room temperature, and then heated to reflux for another 2 h. The reaction was quenched with saturated aqueous Na 2 S 2 O 3 (50 mL).…”

“…The signals of the 1 H NMR spectra were in accordance with the data reported in the literature. 40 Following a reported procedure, 41 tBuLi (2.0 M in heptanes; 4.6 mL, 9.2 mmol, 2.0 equiv) was added dropwise to a solution of 4-bromo-1,2dihydronaphthalene (25s) (0.96 g, 4.6 mmol) in anhydrous THF (20 mL) at −78 °C, over a period of 3 min. The resultant colorless solution was stirred at −78 °C for 0.5 h. Cyclobutanone (0.38 mL, 5.1 mmol, 1.1 equiv) was then added, and the resulting mixture was stirred at −78 °C for 0.5 h. It was then allowed to slowly warm to room temperature.…”

Synthesis of Alkenylboronates from N-Tosylhydrazones through Palladium-Catalyzed Carbene Migratory Insertion

“…In addition, exocyclic alkenylboronates could be prepared by employing the corresponding N-tosylhydrazones containing cyclobutyl, cyclopentyl, or cyclohexyl groups (27−29). A substrate with two different substituents at the α position (R 2 ≠ R 3 ) was also suitable for the reaction, affording the product with E/Z isomers in good yield (30). The low stereoselectivity may come from the low diastereocontrol at the carbene migratory insertion step.…”

Verification of the Major Metabolic Oxidation Path for the Naphthoyl Group in Chemoattractant Receptor-Homologous Molecule Expressed on Th2 Cells (CRTh2) Antagonist 2-(2-(1-Naphthoyl)-8-fluoro-3,4-dihydro-1H-pyrido[4,3-b]indol-5(2H)-yl)acetic Acid (Setipiprant/ACT-129968)

“…As depicted in Scheme 4, the synthesis of building block 9a started with the conversion of α-tetralone 11a to vinyl bromide 14 using bromotriphenoxyphosphonium bromide (TPPBr 2 ). 26 Lithiation of 14 with 1.3 equiv of n-BuLi at −78 °C followed by addition of solid CO 2 (dry ice) as the electrophile gave 3,4-dihydronaphthalene-1-carboxylic acid (15) in 68% yield. 27 Esterification of acid 15 was performed under acidic condition to provide the corresponding ethyl ester 16 in 79% yield.…”