Reaction of olefins with a mixture of phenylselenenyl chloride and mercury(II) thiocyanate. Selective syntheses of .beta.-(phenylseleno)alkyl isothiocyanates as precursors of vinylic isothiocyanates

A general and facile one-pot process of isothiocyanates from amines under aqueous conditions

“…Morevoer, isothiocyanates are pivotal intermediates in organic synthesis, especially in the synthesis of various heterocyclic compounds [ 7 – 8 ] and unsymmetric thioureas [ 9 – 12 ]. Although many synthetic methods for the preparation of isothiocyanates have been reported to date [ 13 – 33 ], most methods suffer from the employment of highly toxic reagents such as thiophosgene and its analogs, the availability of non-commercialized reagents, or from a narrow substrate scope. Recently, a two-step approach, which was named reagent-promoted desulfurylation of dithiocarbamates strategy, has attracted much attention.…”

Electrophilic Addition of XY Reagents to Alkenes and Alkynes

“…47 Regiospecific addition of benzeneselenenyl chloride to allylic alcohols is the key step in a 1,3-enone transposition sequence (Scheme 29).49 cis-Vicinal dichlorides can be prepared from the corresponding alkenes by a process involving trans addition of phenylselenenyl chloride followed by treatment with chlorinating agents, ultimately leading to trans displacement of the seleno moiety (Scheme 30).50 Chlorination with S02Cl2 of the (3-chloroalkyl phenyl selenides derived from terminal alkenes, followed by hydrolysis to selenoxide, followed by elimination leads instead to 2-chloro-1-alkenes (Scheme 31).51 Arylselenenyl chloride, generated in situ from aryl diselenides and NCS, are effective as catalysts for chlorination of alkenes with NCS to give principally a rearranged allylic chloride (Scheme 32).52 Addition of phenylselenenyl chloride and silver trifluoroacetate to nitroalkenes results in regiospecific formation of the phenylseleno-trifluoroacetoxy adducts which can be converted to nitroallylic alcohols (Scheme 33).53 In a related example, successive addition of phenylselenenyl chloride and silver crotonate to alkenes or cycloalkenes affords (3-phenylseleno crotonates which give -y-Iactones upon reaction with triphenyltin hydride (Scheme 34 Phenyl selenocyanate, PhSeCN, adds regio-and stereo-specifically to nucleophilic alkenes such as enamines and ketene acetals giving f3-phenylselenocarbonitriles by a process tenned vicinal cyanoselenenylation. 58 Se-Phenyl areneselenosulfonates, PhSeS02Ar, add to alkenes to give f3-phenylseleno sulfones (selenosulfonation). 55 In alcohol in the presence of metal salts f3-alkoxyalkyl phenyl selenides are fonned.…”

Aminoselenenylation of alkenes: syntheses of β-phenylseleno carbamates and β-phenylseleno cyanamides

“…Prepared from dodec-1-ene (10) and ethyl carbamate in 25% yield, oil; v, , , 3 430,l 710,l 570, 1 500, and 690 cm-'; 6H(200 MHz) 7.53 and 7.26 (5 H, 2 x m, each w3 12.5 Hz), 5.10 (1 H, m, w3 18 Hz, NH),4.09(2H,q,J7Hz),3.40(1H,m,w+ca.30Hz),3.26(1H, q, J 7 Hz), 3.25 (1 H, m, W + ca. 8 Hz) 6,54.6,33.8,31.0,30.4,28.3,22.4,and 22.3 (CH,),14.5,13.9,and 13.8 (Me) 1,72.7,55.4,and 54.4 (CH),33.9,31.9 (x2),30.9,30.3,28.2,25.4,23.6 (x2) 9, 34.3, 33.3, 30.6, 28.6, and 22.6 Carbamatoselenenylation of Cyclododecene (16).--Cyclododecene (16) is a 7:3 mixture of E-and Z-stereoisomer (gas chromatography, 30% carbowax 1500 on chromosorb W; 130 "C). The procedure described for compound (1) (Method A) was followed using cyclododecene (16) (197 mg, 1.18 mmol), ethyl carbamate (4.2 g, 47.5 mmol), and silver tetrafluoroborate (300 mg, 1.54 mmol) in dry dichloromethane (30 ml), and benzeneselenenyl chloride (272 mg, 1.42 mmol) in dry dichloromethane (5 ml) (reaction time 20 h).…”