Isocyanates chlorosulphonyl

Aluminium chloride is often used as a Lewis acid catalyst (equations 68 and 69), although there are many other suitable catalysts (equations 70 and 71). Strong electrophiles such as chlorosulphonyl isocyanate or an aluminium salt do not require catalysis (equations 72 and 73). 

The reactions of chiral allylsilanes with electrophiles to give diastereoselective products has recently been extensively reviewed by Masse and Panek166. An example is shown in equation 99. The reaction of the chiral allylsilanes 142 with phenylsulphenyl chloride (PSC) and chlorosulphonyl isocyanate (CSI) takes place with a diastereoselectivity which increases with the increasing steric bulk of the substituent R167. 

Compound (23) (Expt 8.8) is formed by the reaction of but-l-enyl acetate with chlorosulphonyl isocyanate (Section 4.2.17, p. 425).13 The reaction intermediate is the IV-chlorosulphonyl derivative which is subjected to reduction with alkaline sodium sulphide to yield the product which is isolated as a cis trans (1 1) mixture. But-l-enyl acetate is readily synthesised by acetylation of the enol form of butanal. 

Reaction of the l-aryl-2-phenacylcyclopropanes with chlorosulphonyl isocyanate and subsequent removal of the chlorosulphonyl group with benzenethiol in pyridine affords the 4,5-dihydro-1,3-oxazepines (91) <95SCI939> and in a reaction sequence in which an aziridine is the source of nitrogen, methyl l-benzyloxycarbonylaziridine-2-carboxylate reacts with 2-(N-benzyl-A -/t /7-butoxycarbonyl)aminoethanol to give the derivative (92) which, after removal of the Boc group, is subject to a reductive cyclisation to yield the hexahydro-l,4-oxazepine (93) <95CPBI 137>. 

Among the procedures which have been developed for /J-lactam syntheses (as reviewed [58] [59]) are the cyclization of /3-haIopropionamides [60] from azetidine-2-carboxylic acids and esters [61] the addition of ketenes to Schiff bases [62] ring-contraction procedures [63] [64] [65] [3+1] cyclizations of a-phenylthioacetamide [66] the cyclization of aminoacids [67], and styrene and N-chlorosulphonyl isocyanate [68]. 

The urea, formed in the reaction of the enamine 344 with chlorosulphonyl isocyanate followed by water, cyclizes to the uracil 345, which lacks substituents on the nitrogen atoms (equation 140)170. 

Cycloadditions of electrophilic olefins or cumulenes to vinylcyclopropanes should also be mentioned in this context, since in most cases stepwise reactions starting with an electrophilic attack are very likely. One example operating with chlorosulphonyl isocyanate and providing a seven-membered lactam is depicted in equation 152 however, so far most reactions in this area have a limited synthetic potential. 

The pseudohalide CF3S02NC0 has been synthesized267 by means of a new reaction involving trifluoromethanesulphonamide and chlorosulphonyl isocyanate ... 

Chemistry of the Tricyclic Diterpenoids.—The addition of chlorosulphonyl isocyanate to the methyl esters of levopimaric and neoabietic acids with the formation of C-12 carboxyamides has been described.63 The well documented aromatic substitution reactions of dehydroabietic acid continue to be examined,64 together... 

An efficient cyclization of an aminonitrile under mild conditions (without external heat) is obtained by reacting it with chlorosulphonyl isocyanate (review [3340]) to give a high yield of pyrimidin-2-one [3368] heating with urea is also effective [2774]. The corresponding 4-one is formed in lower yield by heating an (acylamino)nitrile with a primary amine hydrochloride, a t-amine and phosphorus pentoxide [3789], or with acetic anhydride-pyridine [3898]. 

Chlorosulphonyl isocyanate (reviews [324, 3147a, 3340] cyclizes 2-hydroxy-aldehydes and -acetophenones in good yields the corresponding benzophenones are not cyclized in this way. Methyl isocyanate in alkaline solution also reacts with salicylaldehyde to give a high yield of a fused oxazinone. 

Finally, chlorosulphonyl isocyanate has been shown to react with some alkenes to produce a novel series of five-membered cyclic sulphonamides as shown in... 

Chlorosulphonyl isocyanate when reacted with phenols has proven useful in the synthesis of aryl sulphamates228 229 (equation 46). Hydrolysis and decarboxylation of... 

The reaction of a series of o-allylphenols with chlorosulphonyl isocyanate yields a series of o-allylarylsulphonyl isocyanates which, when reacted with 2 amino-4,6-dimethoxy pyrimidines in dioxane at 20 °C, yielded the sulphamates 246. These compounds exhibited... 

A new sulphamoylation agent, N-carbo(trimethylsilyloxy)sulphamoyl chloride (286), prepared by the reaction of (trimethylsilyl)ethanol with chlorosulphonyl isocyanate followed by the elimination of ethylene, has been reported297 (equation 89). This reagent has been used successfully in the preparation of 3-amino-4-A/-alkyl-5-aryloxy-l,2,4,6-thiatriazine-1,1-dioxide (288) (equation 90) by reaction of 286 with N-cyano-N-alkyl pseudoureas (287). The 2-N-alkyl isomer of 288 has also been synthesized. 

Chlorosulphonyl isocyanate is a useful reagent for the synthesis of sulphamides. Reaction of chlorosulphonyl isocyanate with 2-haloethanols (X = Cl, Br) followed by reaction with primary and secondary amines (R = C6H5, 3-N02C6H4, 2-NCC6H4,... 

A parent unalkylated compound in the series has been formed by adding chlorosulphonyl isocyanate in dichloromethane to methyl salicylate at 4-6°C, reacting for a further 3 hours at ambient temperature, removing the solvent and hydrolysing the intermediate at 5-10°C with cold water to give the product shown in 83% yield (ref.28). 

Michael type reaction. Chlorosulphonyl isocyanate adds to epoxides to generate the carbon dioxide inserted oxazolidines (74) or dioxalones (75) depending on the substitution pattern of the epoxide. 

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