N-Sulfinyl-p-toluenesulfonamide

In this article a differentiation of concerted and two-step cycloadditions will not be made although this point will be briefly discussed in the theoretical part. However, products which could be formally formed by a hetero Diels-Alder reaction, but for which a different mechanism has been proven will not be included. Thus, quite recently it has been shown that the formation of an oxazine by reaction of N-sulfinyl-p-toluenesulfonamide and an excess of propanal in the presence of boron trifluoride etherate does not involve a hetero Diels-Alder reaction [37]. 

Despite a considerable amount of recent work on reactions of vinyl silanes with various kinds of imines [48,49], scant attention has been paid to N-sulfonyl imi-nes in this area. A single study of a vinyl silane/N-sulfonyl imine reaction has been published by McIntosh and Weinreb in the context of an approach to the total synthesis of [1, 3]-dioxolophenanthrene structural types of Amaryllida-ceae alkaloids such as narciclasine (137), lycoricidine (138) and pancratistatin (139) [50]. The substrate used in this approach was vinyl silane aldehyde 140, prepared enantiomerically pure in a straightforward manner from L-arabinose (Scheme 26). The N-tosyl imine derived from this aldehyde could be generated in two different ways. The first involved combination of 140 with N-sulfinyl-p-toluenesulfonamide at 80 °C, followed by exposure of the imine to BF3 etherate at 0°C, leading to a single cyclization product 142 in 36% yield. The second procedure was to simply react aldehyde 140 with p-toluenesulfonamide and BF3 etherate (-78°C -rt) to afford a 9.5 1 mixture of 142 144 in -80% yield. It was pro-... 

Weinreb and Sisko have reported the first examples of Diels-Alder reactions of Af-tosyl imines derived from enolizable aldehydes [12]. The imines were generated in situ from the aldehyde, N-sulfinyl-p-toluenesulfonamide and boron trifluoride etherate. Two examples of these cycloadditions are shown in Egs. (50) and (51). It was also possible to effect the cycloaddition intramolecularly [Eq. 

Mock and Nugent investigated the mechanism of the [4 -I- 2] cycloaddition of N-sulfinyl-p-toluenesulfonamide (9) and the isomeric 2,4-hex-adienes 10,11, and 12 in detail (Scheme l-II)." These workers determined the relative stereochemistry of the resulting adducts and proposed a stepwise dipolar mechanism based primarily on the difference in sulfur stereochemistry between adducts produced from dienes 11 and 12. 

Styrylindoles, 100 Sulfamic acid, 28 oi-Sulfenyl esters, 150 v-Sulfenyl lactones, 150 Sulfinamides, 100-101 SulTinates, 388-389 N-Sulfinyl-p-toluenesulfonamide, 50 Sulfonyl cMorides, 58 Sulfoxides, 3, 58 Sulfur dioxide, 346-346 Sulfuric acid, 347-348 Sulfuiyl chloride, 349-350 Super Hydride, 215-216, 307... 

Optically pure ( + )-p-tolyl methyl sulfoxide allowed to react 3.5 hrs. at 0° with N-sulfinyl-p-toluenesulfonamide in pyridine ( —)-N-p-toluenesulfonyl S-methyl S-p-tolyl sulfilimine (Y 95% optical purity 98%) allowed to stand 24 hrs. at 16° with satd. methanolic KOH ( + )-p-tolyl methyl sulfoxide (Y 94% optical purity 96%). J. Day and D. J. Cram, Am. Soc. 87, 4398 (1965). ... 

N-Phenylhenzamidine allowed to react at room temp, with 2 moles N-sulfinyl-p-toluenesulfonamide 3- phenyl -1- p - toluenesulfonimino -1,2,4-benzothiadia-... 

The A -SES group can be incorporated by treating an aldehyde with (V-sulfinyl-p-trimethylsilylethanesulfonamide (SESNSO) (13), which can be made by treating the sulfonamide (12) with Thionyl Chloride and a catalytic amount of N,N-dichloro-p-toluenesulfonamide (eq 7) (see also N-Sulfinyl-p-toluenesulfonamide). The )V-sulfonyl imine can be used in situ in a number of reactions. For example, the A(-sulfonyl imine from aldehyde (14) reacts with 2,3-dimethylbutadiene (eq 8) to give the Diels-Alder adduct (15). Treatment of (15) with fluoride ion affords the bicyclic lactam (16). Also, the IV-sulfonyl imine derived from isobutyraldehyde and (13) reacts with Vinylmagne-sium Bromide to provide the allylic SES-sulfonamide (17) in 65% yield (eq 9). ... 

Thioxo-5-phenyl-3H-l,2-dithiole in abs. chloroform stirred and treated with N-sulfinyl-p-toluenesulfonamide in the same solvent, and refluxed 5 hrs. 3-p-toluenesulfonylimino-5-phenyl-3H-l,2-dithiole. Y 70%. - 3-Sulfonylimino-... 

One synthetic problem in the imino Diels-Alder reactions is the imines stability under the influence of Lewis acids. It is desirable that the imines activated by Lewis acids are immediately trapped by dienes or dienophiles [57]. In 1989, Sis-ko and Weinreb reported a convenient procedure for the imino Diels-Alder reaction of an aldehyde and a 1,3-diene with M-sulfinyl p-toluenesulfonamide via N-sulfonyl imine produced in situ,by using a stoichiometric amount of BF3.OEt2 as a promoter [64]. 

In the reaction of Af-sulfinyl-p-toluenesulfonamide with methyl-t-butylcarbodiimide, the reaction proceeds across the less sterically hindered C=N group to give N-methylsulfinylamine and Af-p-toluenesulfonyl-A -t-butylcarbodiimide °. 

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