Oxathiolanes, substituted

The desUylation strategy has been used for the cycloaddition of the parent thiocarbonyl yhde la with aldehydes and reactive ketones. The product obtained using A-methyl-3-oxoindolinone as the trapping agent corresponds to the spiro-cyclic compound 125 (168). Thioketene (5)-methylide (127) was reported to react with aromatic aldehydes and some ketones to furnish 2-methylene-substituted 1,3-oxathiolanes (128) (51) (Scheme 5.42). 

The Cu-catalysed ring expansion of 2-substituted 1,3-oxathiolanes with ethyl (triethylsilyl)diazoacetate affords 2,3-disubstituted 1,4-oxathianes with variable diastereoselectivity the intermediacy of a Cu carbene and of a S-ylide is proposed <02CC346>. 

Patent Substituted 1,3-Oxathiolanes with Antiviral Properties... 

The ring expansion of appropriately substituted 1,3-oxathiolane sulfoxides and 1,3-dithiolane sulfoxides can be performed under acidic or neutral conditions. This sequence gives, in good yields, the corresponding substituted 2,3-dihydro-l,4-oxathiins and 2,3-dihydro-1,4-dithiins <84TL757,... 

Ytterbium triflate in an ionic liquid is an efficient catalyst for reaction of aldehydes and ketones with mercaptoethanol to form 2-substituted 1,3-oxathiolanes <04SL2785> and K-10 montmorillonite has been used for the same reaction where it shows selectivity for aldehydes over ketones <04SL1592>. The compound 76 has been used to introduce a mercapto acid unit into peptide analogues <04S1088> and the diastereoselectivity of addition of the anion of 77 to carbonyl compounds has been examined <03JHC979>. 

Heating cyclic mono-, di- or tri-thiocarbonates, usually in the presence of base, gives thiiranes and carbon dioxide, carbon oxysulfide or carbon disulfide respectively. The methiodide salts of 2-methylimino-l,3-oxathiolanes are converted to thiiranes with high stereoselectivity, except for 5-aryl-substituted oxathiolanes (Scheme 146) (80LA1779). Flash vacuum thermolysis of l,3-oxathiolan-5-ones causes loss of carbon dioxide and nearly quantitative formation of thiiranes of inverted configuration (Scheme 147) (80JA744). For example, thermolysis of c/s-2,4-diphenyl-1,3-oxathiolan-5-one gives trans-2,4-diphenyl-thiirane. 

Oxathiolane 3,3-dioxide (332) metallates in its 2-position to yield an anion which reacts with various electrophiles (alkyl halides and carbonyl compounds) to give substituted oxathiolanes (333) in good to excellent yield (79TL3375). Pyrolysis of these alkylated products affords the corresponding aldehydes or 2-hydroxyaldehydes in addition to sulfur dioxide and isobutylene (Scheme 71). The oxathiolane (332) thus becomes another member of the already burgeoning class of carbonyl anion equivalents. 

Substituted A,A-dialkyl(cycloalkyl)furfurylamines and their quaternary salts, 2-substituted 1,3-dioxolanes, oxathiolanes, and -dithiolanes, as antagnoists and muscarinic receptors 98F1. 

Lewis acid SnCLj-assisted reaction between the l,3-thiazole-5-thione 434 and /ra r-2,3-dimethyloxirane led to the m 4,5-dimethyl-l,3-oxathiolane 435 The same Lewis acid enabled a second addition of /ra/ -2,3-dimcthyloxirane onto the C—N bond of the 1,3-thiazole ting of 434, leading to the formation of the tetrahydro-2//-thiazolo[2,3- ]-oxazole adduct 436 (Equation 200) <2000HCA3163>. Condensation of 2,4-dinitroimidazole, 8-bromotheophylline, and 8-bromoadenine with substituted methyloxiranes involved sequential A -alkylation-r/wo-substitution and furnished a series of 2,3-dihydro-imidazo[2,l- ]oxazole derivatives 437, 438, and 439 (Equations 201-203) <2000CCC1126, 2000EJ03489, 2005TL3561, 2004JHC51>. 

A monofluorination of 2-substituted-l,3-oxathiolan-5-ones (Scheme 116) [216], 2-substituted dithiolanones [217], thi-azolidinones [218], and dihydrochro-manone or thiodihydrochromanone... 

An extensive review of the hetero-Diels-Alder reactions of 1-oxabuta-1,3-dienes has been published. Ab initio calculations of the Diels-Alder reactions of prop-2-enethial with a number of dienophiles show that the transition states of all the reactions are similar and synchronous.Thio- and seleno-carbonyl compounds behave as superdienophiles in Diels-Alder reactions with cyclic and aryl-, methyl-, or methoxy-substituted open-chain buta-1,3-dienes.The intramolecular hetero-Diels-Alder reactions of 4-benzylidine-3-oxo[l,3]oxathiolan-5-ones (100) produce cycloadducts (101) and (102) in high yield and excellent endo/exo-selectivity (Scheme 39). A density functional theoretical study of the hetero-Diels-Alder reaction between butadiene and acrolein indicates that the endo s-cis is the most stable transition structure in both catalysed and uncatalysed reactions.The formation and use of amino acid-derived chiral acylnitroso hetero-Diels-Alder reactions in organic synthesis has been reviewed. The 4 + 2-cycloadditions of A-acylthioformamides as dienophiles have been reviewed. ... 

Water-soluble PPEs have been made by the suitable choice of ionic and highly hydrophilic side chains. These PPEs will play a role in bio-type sensing applications (vide infra). A clever example is Schanze s synthesis of a sulfonato-substituted PPE [40, 41]. The NaOH-promoted reaction of [1, 2]oxathiolane-2,2-dioxide with 2,5-diiodohydroquinone gives a bis-sulfonate that can be coupled (Pd-catalyzed) to 1,4-diethynylbenzene to form a water-soluble PPE (Scheme 4) Table 6, entry 1). In a similar approach, Schanze et al. [42] made a... 

The enolates of l,3-dioxolan-4-ones 1 and l,3-oxathiolan-4-ones2, which are y-lactones substituted with a heteroatom, can be prepared using normal conditions (LDA, THF) and subsequently alkylated. If one takes, e.g.. a nonracemic a-hydroxy acid such as lactic acid 3, then on formation of the heterocycles 1 (R1 = CH3 R2 = alkyl) chirality is transferred from the a-po-sition (C-5) in the starting acid to C-2 in 1, forming (2R,5R)-4 and (2S,5R)-5. If 4 and 5 are easily separable or, even better, if one of them is formed diastereoselectively from 3 then 4 and/or 5 can be transformed to the respective enolates 6 and 7 and alkylated with R X. 

The fully saturated 1,3-dioxolanes and 1,3-oxathiolanes are conformationally labile rings and have been the subject of intense spectral investigation. In particular, 1,3-dioxolanes have a special place in NMR history. It was during a study of 4-substituted 2,2-dimethyl- 1,3-dioxolanes that geminal and vicinal couplings in aliphatic systems were shown to have opposite signs, a result which contradicted the theoretical predictions of the time (61JA3901). 

There has been no effort to study systematically a series of compounds. The lower dioxoles and oxathioles are liquids, insoluble in water but soluble in most organic solvents. 1,3-Dioxole boils at 51 °C at atmospheric pressure, while 2,2-dimethyl substitution raises this to 72-73 °C. No boiling point has been reported for 1,2-dioxolane and the only report for 1,2-oxathiolane indicates that it codistills with chloroform at 20 °C (0.1 mmHg). 1,3-Dioxolane boils at 75 °C (760 mmHg) and the introduction of sulfur raises the boiling point such that 1,3-oxathiolane boils at 132-136 °C (760 mmHg). 

For many of these systems the parent compounds are unknown or known only either in highly substituted or oxidized forms. In some cases, such as the aromatic 1,3-oxathioles, the mesoionic oxathioles and 1,2-oxathiolane, there is only one synthetic method. The synthesis of these compounds, therefore, will be found in earlier sections. Further, the... 

Amino substituted)-l,3-dioxolanes and -oxathiolanes are readily available as shown in equation (46), while derivatives of the corresponding 2-ylium species are also easily prepared (equation 47) (72CRV357). A 4-amino-l,2-oxathiolane 2-oxide was recently prepared in high yield by total synthesis (81JOC5408). 

Oxo-1,3-oxathiolanes arc obtained from f(-o o esters or 1,3-diketoncs when treated with chlorocarbonylsulfenyl chloride at 80-100 Finally, hctcrocycles containing phosphorus have also been synthesized by substitution reactions, forming a C-O bond. ... 

The stable 1,2-oxathiolane 34 was formed by cycloaddition of the sulfine thiofluorenone j -oxide 133 to ( )-cyclooctene (Scheme 5) <1998JA4861>. Iron-substituted 1,2-oxathiolane 2-oxides 39 and 40 were formed in 94% yield by treating the corresponding cyclopropyliron compound 134 with SO2 in MeCN <19980M5534> while reaction of propargyliron compounds 135 with SO2 or SO3 gave the compounds 48 and 50, respectively (Scheme 5) <2000JOM(598)150>. 

The crystal structures of the 1,3-oxathiolane derivatives 50 and 51 have been reported <2005EJ01613>. The stereoselectivity of the reaction of benzo-l,3-dithiole A-oxide with various electrophiles has been examined, and the X-ray structures of a number of different diastereomeric products including 52-55 have been determined <2001T10365>. Finally, X-ray diffraction studies have been reported for substituted benzoxathiole 1,1-dioxides 56 and 57 <1996AP361>. 

---