Rasta resin–triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions

Summary Heterogeneous polymer-supported triphenylphosphine oxides based on the rasta resin architecture have been synthesized, and applied as reagent precursors in a wide range of halogenation reactions. The rasta resin–triphenylphosphine oxides were reacted with either oxalyl chloride or oxalyl bromide to form the corresponding halophosphonium salts, and these in turn were reacted with alcohols, aldehydes, aziridines and epoxides to form halogenated products in high yields after simple purification. The polymer-supported triphenylphosphine oxides formed as a byproduct during these reactions could be recovered and reused numerous times with no appreciable decrease in reactivity.


General procedure for aldehyde halogenation reactions using 16
To 16 (0.3 g, 0.3 mmol) was added chloroform (3 mL) in a round-bottom flask. After 10 min, oxalyl chloride or oxalyl bromide was added (0.3 mmol). The reaction mixture was magnetically stirred at room temperature. Upon cessation of gas evolution, 6 was added (0.1 mmol) and the reaction mixture was heated to reflux. After 72 h, the reaction mixture was cooled to room temperature and then filtered. The solid on funnel was washed with dichloromethane (3 × 5 mL). The filtrate was concentrated under reduced pressure to afford the crude product. The crude product was purified by flash silica gel column chromatography using 5% ethyl acetate in hexanes as the eluent.

1-(Dibromomethyl)-4-methylbenzene (7Fb,
To 16 (0.6 g, 0.6 mmol) was added dichloromethane (5 mL) in round-bottom flask. After 10 min, oxalyl chloride or oxalyl bromide was added (0.6 mmol). The reaction mixture was magnetically stirred at room temperature. Upon cessation of gas evolution, 8 was added (0.5 mmol), and the reaction mixture was heated to reflux. After the reaction was complete according to TLC analysis, the mixture was cooled to room temperature and filtered. The solid on funnel was washed with dichloromethane (3 × 10 mL), and the filtrate was concentrated to afford the desired product 9 in an essentially pure state based on 1 H and 13 C NMR spectroscopic analyses. S13 Table 3, entry 1) [16]. Isolated yield: 95%.   Table 3, entry 11) [21]. Isolated yield: 93%.

General procedure for epoxide halogenation reactions using 18
To 18 (1.3 g, 1.2 mmol) was added chloroform (10 mL) in a round-bottom flask. After 10 min, oxalyl chloride or oxalyl bromide was added (1.1 mmol). The reaction mixture was magnetically stirred at room temperature. Upon cessation of gas evolution, 10 was added (0.5 mmol) and the reaction mixture was heated to reflux. After the reaction was completed as monitored by TLC, the mixture was cooled to room temperature and filtered. The solid on funnel was washed with dichloromethane (3 × 10 mL). The solvent of filtrate was removed to afford the desired product 11 in an essentially pure state based on 1 H and 13 C NMR spectroscopic analyses.

X-ray report of N-(2-chlorocyclohexyl)-4-methylbenzenesulfonamide
The  about twice as large as those based on F, and R-factors based on ALL data will be even larger.

S82
For Z = 4 and F.W. = 332.25, the calculated density is 1.489 g/cm 3 . Based on a statistical analysis of intensity distribution, and the successful solution and refinement of the structure, the space group was determined to be: P 2 1 /c (#14) The data were collected at a temperature of 23(1)°C to a maximum 2 value of 66.1°.
Of the 17462 reflections that were collected, 2616 reflections were unique. (R int = 0.0738); equivalent reflections were merged.

Figure 3
The ORTEP plot of the compound was shown at 50% probability thermal ellipsoids with the atom numbering scheme.