Oxathiane Derivatives

Compounds 385 and 386 were prepared from quinones with a chlorine atom and an aziridino group in ortho positions after treatment with sodium hydroxyethylmercaptide (57AG252). Oxathiin S,S-dioxide quinone (387) was obtained from the bis(2,5-dihydroxyphenyl)sulfone in the presence of sodium chlorate and sulfuric acid (73CB798). 

Synthetically, 2,3-dihydro-l,4-benzoxazine-6,7-diones (391) can be prepared from 2,5-bisanilino-3-acetyl- (or methoxycarbonyl)-l,4-benzoquinones and substituted 2-hydroxyethylamines (73T2881). 2-Amino-3-aziridino-1,4-naphthoquinone, when heated in aqueous sodium hydroxide, is claimed to give 392 (69FES732), and the benzo analog was prepared from 2,3-dichloro- 

4- naphthoquinone and tosylated o-aminophenol (21CB259). Compound 392 was prepared from 1,4-naphthoquinone and /S-alanine (66MI2). When 

5- dihydroxy-l,4-benzoquinone was condensed with various nitroso compounds, derivatives of 393 were obtained (65T389). 

An antibiotic, ansathiazin (394), was isolated from Streptomyces albo-longus, the structure followed from its transformations and spectroscopic data (86E1167). 

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Stereochemically, even more interesting are the bis-l,3-oxathiane derivatives 98 and 99 <2005STC369>. All compounds are chiral and the chiral elements are carbons C-2/C-2 and the 1,3-oxathine moieties themselves (Equation 9). Due to the bis-structure, compounds 98 and 99 exhibit both homochiral iZR,2 R ZS,Z S) and hetero-chiral (2R,Z S) isomers (Scheme 4) and they reveal rapid equilibration in solution via open-chain intermediates, thereby preventing separation and individual analysis of the isomers in solution. In the solid state, the compounds crystallized either as unique heterochiral isomers or as a mixture of the two as a solid solution. 

Grosu and co-workers also studied the complex configurational and conformational aspects of the unique stereochemistry of substituted spiro-l,3-oxathiane derivatives 100-102 by NMR spectroscopy <2001T8751>. 

The C-H bond-dissociation energies Z>c-h of the acetals 130 and 131, monothioacetal 132, and the dithioacetal 133 (Figure 7) were calculated from experimental reaction kinetic data <2005MI379>. The C-H dissociation energies of the 1,3-dithiane derivative 133 proved to be lowest, followed by the 1,3-oxathiane derivatives 132,... 

Liquid crystal polymers having 1,3-dithiane or 1,3-oxathiane rings as mesogenic side groups exhibit the extremely important liquid crystal phase at around room temperature <1999MI335>. 1,3-Oxathianes have also been applied as perfumery and flavoring ingredients other derivatives exhibit excellent herbicidal activity and 1,3-oxathiane derivatives have been employed as corrosion inhibitors for steel. 

The optically active 1,3-oxathiane derivative 81, synthesized as a chiral auxiliary (cf. Scheme 30), has been reported. The isomers were assignend by X-ray diffraction in the solid state trans) and by NOE experiments in solution cis) (97CPB778). Rules for the specification of the absolute configuration of the enantiomers R or S) for 1,3-oxathianes and other heterocycles with at least two hetero atoms were proposed and proved... 

In addition, the X-ray crystal structures of two 1,4-oxathiane derivatives were published (00AX1510, 01AX560) the di-axial conformation of the hydroxymethyl group in position 3 and of the l,9-dihydro-6//-purin-6-one group in position 6 in compound 82 is surprising (01AX560) (cf. Scheme 30). The X-ray structures of the sulfones of the isomeric 2,6-di-OEt-3-OMe-l,4-oxathianes were published (00CEJ1858) the 4,4-dioxa-... 

The methods of synthesis, the configurational and conformational aspects of the stereochemistry and the main spectral properties and reactions of 1,3-oxathiane derivatives were reviewed after submitting the manuscript (2003H1477). 

Reactions subsequent to lithiation at C-2 of the 1,3-oxathianes derived from 5-hydroxy-1-tetralone 45 <03EJO337> and from myrtenal 46 <03JOC6619> result in the equatorial product. 

Syntheses, structural analysis, and reactivity of 1,3-oxathiane derivatives 03H-(60)1447. 

X-ray diffraction studies have suggested that the anomeric effect operates in 2-phosphinoyl derivatives of the saturated heterocycles, where the 2-substituent has no lone electron pairs. For example, in 2-diphenylphosphinoyl-l,3-dithiane, the substituent occupies an axial position, in contrast to the 1,3-dioxane and 1,3-oxathiane derivatives, where the same substituent occupies an equatorial position <84JOC3026,88JOC3609,88TL6801>. 

The addition of a variety of organometallic reagents to imines and hydrazones (74) of 2-acyl-1,3-oxathianes derived from pulegone proceeds with very high diastereoselectivity (Equation (39)), the addition of lanthanide salts reversing the sense of asymmetric induction <90JA8189,94CL831). 

The empirical validity of these generalizations has been substantiated by a study of a series of 1,4-oxathian derivatives in which the configuration and conformation of some members was established by chemical and X-ray methods. The parameters of compounds... 

Table II. Isolated Yields of Aldehydes and Hydroxythiol from Deprotection of Oxathiane Derivatives...

Preparation of and Transformations of Oxathianes derived from Pulegone. 

The Finnish group have reported a large number of equilibrations on 1,3-oxathian derivatives. The value that they obtain for the equilibrium (64a) (64b) (—AG = 1.16kcalmol i) is in agreement with an estimate made by... 

Reports have appeared on the preparation and on the Wittig-Homer reactions of (l,3-dithian-2-yl)phosphonium salts, e.g. (137). Cyclocondensation of 0(CH2SS03Na)2 with thiolesters gave the 1,3,5-oxathian derivatives (138). 1,2-Dithiols and 2-mercaptoethanols were added to CFjCN to give 1,3-dithiolans, e.g. (139), and 1,3-oxathiolans, respectively. Several 2-ferrocenyl-1,3-dithiolans, -1,3-oxathiolans, and -1,3,5-trithians have been prepared. ... 

The j -BuLi-(—)-sparteine combination is widely used in enan-tioinductive organic reactions. 4.H7-i22 Benzylic asymmetric alkylation may thus be achieved by subsequent treatment with alkyl halides, alkyl tosylates, and allyl tosylates 1,3-Oxathiane derivatives shown in eq 50 may be lithiated and quenched with electrophiles. An interesting aspect of this reaction is the equatorial stereoselectivity, which is independent of the size of the electrophile introduced. ... 

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