Cyclic sulfates synthesis

The final example in this section is the synthesis of a tristetrahydrofuran 2-606 described by the group of Rychnovsky [313]. Here, the tris(sulfate) 2-605 was converted into 2-606 by simply heating it in a mixture of MeCN and H20 (Scheme 2.138). The domino reaction is most likely initiated by deprotection of the primary alcohol, which then attacks the adjacent sulfonate unit in a SN2-type manner to afford the first furan moiety. Under the reaction conditions the formed acyclic sulfate is hydrolyzed affording a free secondary alcohol which then attacks the next adjacent cyclic sulfate unit. Overall, the SN2/hydrolyzation sequence proceeds three times to finally provide the poly(tetrahydrofuran) 2-606 as a single isomer in 93 % yield. 

The synthesis of enantiomerically pure D-manno and L-gluco iminosugars 183 and 184, respectively, was achieved via reduction of an isoxazoline to an amine, which subsequently acts as a nucleophile in a spontaneous opening of the cyclic sulfate moiety <06JOC894>. 

A review of cyclic sulfites and sulfates in organic synthesis includes many examples of 1,3,2-dioxathiolane 5-oxides and 5,5-dioxides <0OT7O51>. Reaction of cyclic sulfates such as... 

Few examples of this class of compound have been reported, although the cyclic sulfate 158 and the cyclic sulfite 159 have been reported as intermediates in carbohydrate and nucleoside synthesis, repectively <1996JOC480, 2001J(P1)1855>. 

T. J. Tewson and M. Soderlind, I-Propenyl 4,6-0-benzylidene-g-i>mannopyranoside-2,3-cyclic sulfate A substrate for the synthesis of [F-18] 2-deoxy-2-fluoro-n-glucose, J. Carbo-hydr. 4 529 (1985). 

Treatment of diethyl malonate and related compounds with 1,2-dihaloethane in the presence of base constitutes a classical method of cyclopropane synthesis296"300. The reaction can be conveniently carried out under PTC conditions. An improved method utilizing solid-liquid phase transfer catalysis has been reported298. The reaction of dimethyl or diethyl malonate with 1,2-dibromoalkanes except for 1,2-dibromethane tends to give only low yields of 2-alkylcyclopropane-l, 1-dicarboxylic esters. By the use of di-tm-butyl malonate, their preparations in satisfactory yields are realized (equation 134)297. The 2-alkylcyclopropane derivatives are also obtained from the reaction of dimethyl malonate and cyclic sulfates derived from alkane-1,2-diols (equation 135)301. Asymmetric synthesis... 

Alternatively, the remaining sulfate ester of 70 may serve as a leaving group for a second nucleophilic displacement reaction. When this displacement is by an intramolecular nucleophile, a new ring is formed, as was first shown in the synthesis of a cyclopropane with malonate as the nucleophile [68] and of aziridines with amines as the nucleophiles [76]. The concept is further illustrated in the double displacement on (/J,/ )-stilbenediol cyclic sulfate (72) by benzamidine (73) to produce the chiral imidazoline 74 [79]. Conversion of the imidazoline (74) to (.V,.S )-stilbenediaminc 75 demonstrates an alternative route to optically active 1,2-diamines. Acylation of 75 with chloroacetyl chloride forms a bisamide, which, after reduction with diborane, is cyclized to the enantiomerically pure trans-2,3-diphenyl- 1,4-diazabicy-clo[2.2.2]octane (76) [81],... 

H. G. Bazin, T. Polat, and R. J. Linhardt, Synthesis of sucrose-based surfactants through regioselective sulfonation of acylsucrose and the nucleophilic opening of a sucrose cyclic sulfate,... 

P. A. M. van der Klein, W. Filemon, G. H. Veeneman, G. A. van der Marel, and J. H. van Boom, Highly regioselective ring opening of five-membered cyclic sulfates with lithium aluminium azide synthesis of azido sugars, J. Carhohydr. Chem., 11 (1992) 837-848. 

A. Vargas-Berenguel, F. Santoyo-Gonzalez, J. A. Calvo-Asin, F. G. Calvo-Flores, J. M. Exposito-Lopez, F. Hernandez-Mateo, J. Isac-Garcia, and J. J. G. Martinez, Synthesis of 6-deoxyheptose derivatives via cyclic sulfates and oxetanes, Synthesis, (1998) 1778-1786. 

Reaction of cyclic sulfates with intramolecular O-nucleophiles leads to cyclic ethers and other heterocycles (Table 1). For example, a hydrolysis of compound 39 has produced predominantly the cyclic alcohols 41 (Scheme 4) < 1995JA12873 >. When the reaction was buffered with pyridine, the sulfate ester 40 was isolated rather than the free alcohol. An alcohol function in an intermediate product may give a route to a polysulfate cascade cyclization, which has been successfully realized in the synthesis of poly(tetrahydrofurans) (Table 1) <1995JA12873>. 

A general strategy for the transformation of cyclic sulfates into vicinal diamines has been developed (Scheme 7) <1995TL9241>. This method has been extended to the synthesis of unsymmetrical diamines and various other amine derivatives by the controlled introduction of a second nucleophile into the reaction sequence <1995TL9241>. 

The syntheses and reactions of 1,3,2-dioxathiolane. Y-oxides and 1,3,2-dioxathiolane. Y,.Y-dioxides have been discussed in comprehensive reviews <1997AHC89, 2000T7051>. In publications on organic synthesis these compounds are usually named cyclic sulfites and cyclic sulfates, respectively (Sections 6.05.5 and 6.05.6 Tables 1-7). 

The heading substitution reactions has been used to describe the conversion of a stereogenic center to another. Of course, this means that the substrate stereogenic center has had to be obtained by one of the reaction types outlined earlier, from the chiral pool, or by resolution. Reactions that fall into this category include epoxide and cyclic sulfate openings and iodolactonizations (Chapter 22). Perhaps the most important reaction of this type for asymmetric synthesis is allylic substitution in the presence of a transition metal catalyst. 

An alternative to the use of cyclic sulfates is the use of cyclic carbonates, as illustrated for the synthesis of 1,2-amino alcohols (Scheme 9.29).176... 

B. B. Lohray, Cyclic Sulfites and Cyclic Sulfates Epoxide Like Synthons, Synthesis 1992, 1035-1052. J. B. Sweeney, Aziridines Epoxides Ugly Cousins Chem. Soc. Rev. 2002, 31, 247-258. 

Chiral cyclic sulfates in synthesis of sulfates labeled with 170 and lsO 91PS(59)66. 

B. B. Lohray, Cyclic sulfites and cyclic sulfates Epoxide like synthons, Synthesis 1992,1035-1052. 

The synthesis of the 4,5-dimethoxy-l,3,2-dioxathiolane 2,2-dioxide (98) from perfluoro-2-butene involved reaction with sodium methoxide, resulting in a mixture of cis and trans isomers of the vinyl diether (197). Subsequent action of sulfur trioxide on (197) gave, probably via the 1,2-oxathietane 2,2-dioxide (198), the cyclic sulfate (98) (77JA1214), a convenient precursor to hexafluorobiacetyl (c/. Section 4.33.3.3.1). 

Trithioles and 1,3,2-dioxathiolanes. 1,2,3-Trithiolanes are prepared by reaction of alkenes with elemental sulfur . The synthesis of 1,3,2-dioxathiolane -oxides (cyclic sulfites) and 1,3,2-dioxathiolane S, -dioxides (cyclic sulfates) is discussed in comprehensive reviews <1997AHC(68)89, 2000T7051>. The most widely used method for the preparation of 1,3,2-dioxathiolane A-oxides 557 is the reaction of the corresponding 1,2-diols 556 with thionyl chloride in the presence of pyridine or triethylamine (Scheme 251). More reactive 1,3,2-dioxathiolane S,A-dioxides 558 are usually obtained by oxidation of sulfites 557 with sodium periodate, which is mediated by ruthenium tetroxide generated in situ from a catalytic amount of ruthenium trichloride <1997AHC89, 2000T7051, CHEC-III(6.05.10.3)183>. 

A scale-up synthesis of isosteric phosphonate analogue (178) of mannose-6-phosphate (M6P) has been perfonned via regioselective nucleophilic displacement of the protected 4,6-cyclic sulfate precursor (179) by lithiated dialkyl methylphosphonates in the key step. ... 

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