Thiocarbonyl 5-imides

Thiocarbonyl -imides, R2C=S=NR, were first synthesized as reactive intermediates by Burgess and Penton in 1973 by dehydrochlorination of fV-sulfenyl chlorides 1 at -78 °C in THF. In the absence of dipolarophiles the red solution of the thiocarbonyl 5-imide 2 undergoes cyclization at about -30 °C to form the oxathiazole derivative 3. 

The thiocarbonyl 5 -imides are usually generated in situ however, N-(adamantyl)hexafluorothioacetone, (CF3)2C=S=NR (R = adamantyl), was found to be stable at room temperature.  

Thiocarbonyl S-imides are excellent dipols in [3+2] cycloaddition reactions. Also [2+4] cycloaddition reactions of thiocarbonyl -imides are known. 

The thiocarbonyl 5-imide4, generated in the reaction of 2,2,4,4-tetramethyl-3-thioxocyclo-butanone with phenyl azide, is intercepted with fumarodinitrile to give the cycloadduct 5 in 25 % yield.  

Other reactive olefins, such as enamines and vinyl ethers also participate as dipolarophiles in their reaction with thiocarbonyl 5-imides. Even fulvenes undergo [3+2] cycloaddition reactions. 

---

Organic Azides. The 1,3-dipolar cycloadditions of 1 with organic azides require elevated temperatures. T)q)ical products of the reactions of thioketones are W substituted imines, which are formed after decomposition of the initially formed 1,2,3,4-thiatriazole derivates. However, in the case of 1 and aryl azides, the intermediate thiocarbonyl 5-imides (28) intercept 1 to give dispiro-l,4,2-dithiazoles (29) (eq 13).22... 

In a three-component reaction with 1 and fumaronitrile dissolved in phenyl azide, the 7V-phenyl substituted thiocarbonyl 5-imide (28, Ar = Ph) cycloadds to fumaronitrile to give the corresponding 1,2-thiazolidine derivative. ... 

Thiocarbonyl S-Imides. In eq 13, the interception of a thiocarbonyl S-imide generated in situ from 1 and organic azides is outlined. Similarly, thiocarbonyl 5-imide (30, eq 14) undergoes a 1,3-dipolar cycloaddition with 1 in competition with the formation of the unstable thiaziridine 31, and the corresponding 2,5-dispiro-l,4,2-dithiazolidine (43) and imine 32 are obtained (eq 18). A similar reaction with methyl dithiobenzoate, in which along with 1,2,4-trithiolane (34) a 1,4,2-dithiazolidine of type 43 is formed, is also reported. ... 

Die Behandlung von Diphenyl-thiophosphinsaure-(dimethylamino-thiocarbonylamid) mit Diazomethan liefert dagegen cin Gemisch aus Diphenyl-lhiophosphmsaure-[(dimethylumino-thiocarbonyl)-imid -rnethylestcr und Diphenyl-thiophosphinsdure- [(dimethylamino-methyllhio-methylen)-amid] 1" ... 

Thiocarbonyl Ylides, Thiocarbonyl Imides, and their Selenium Analogues... 

The thiation procedure described here is an example of a general synthetic method for the conversion of carbonyl to thiocarbonyl groups. Similar transformations have been carried out with ketones, carboxamides,esters,thioesters, 1 actones, " thiol actones, - imides, enaminones, and protected peptides. ... 

Conventional conversion of amide, lactam, imide, and urea carbonyl groups into enaminones, enamino esters, or enamino nitriles requires prior activation of the carbonyl groups either by alkylation to imino ethers, followed by reaction with activated methylene groups, or by thiation, e.g. with P2S5, to thiocarbonyl groups followed by alkylation (and possibly also oxidation), and, again, subsequent reac-... 

One of the most important parameters to determine the reactivity is the distance between the thiocarbonyl sulfur (S) and the alkenyl carbon atom (C6) in Table 1, because a new bond will be formed between these two atoms at the initial step of the photoprocess. The actual distance of the (Z,E)-conformation imide la is 3.59 A, which is closely placed and is almost the same as the sum of the van der Waals radii 3.50 A. In the (EyE) conformation, the atomic distances are longer than that of la, and are 4.13 A for Ic and 4.32 A for Id. For the second step of cyclization, the atomic distance between the thiocarbonyl carbon (C2) and the alkenyl carbon (C5) is in the range from 3.00 to 3.11 A, which is much smaller than the sum of the van der Waals radii 3.40 A. From this geometrical consideration of the site of the new bond formation, it is expected that the reaction leading to thietane will smoothly progress. 

Closely related to the already mentioned electrocyclizations of N-acyl thione S-imide (see Section 4.14.9.2) are some intermolecular cycloadditions involving this unusual class of 1,3-dipoles. Thus, the thione-S-imide intermediate (233) is probably involved in the formation of spirodithiazoline derivative (234) from the thione (235) and aryl azides <93HCA2147>. Also fluorenone-S-/ -tosylimide affords with carbonyl or thiocarbonyl compounds (R H) the corresponding oxathia- or dithia-zolidine derivatives (236) (Y = O or S) <80BCJ1023> (Scheme 44) (see also Section 4.14.6.1). 

Thiocarbonyl ylides (1) belong to tbe family of sulfur-centered 1,3-dipoles cbaracterized by tbe presence of two sp C atoms attached to tbe sulfur atom. Formal replacement of one of the C atoms by heteroatoms such as NR3, O, and S lead to the other representatives of the family, namely, thiocarbonyl S-imides (2), S-oxides (sulfines) (3), and S-sulfides (thiosulfines) (4), respectively. 

Numerous examples involving the preparation of tetrahydrothiophenes via [3 + 2] cycloaddition of thiocarbonyl ylides with electron-poor alkenes have been reported. Thiobenzophenone (5)-methylide (16), generated from 2,5-dihydro-1,3,4-thiadiazole (15) and analogous compounds, react with maleic anhydride, N-substituted maleic imide, maleates, fumarates, and fumaronitrile at —45°C (28,91,93,98,128,129). Similar reactions with adamantanethione (5)-methylide (52) and 2,2,4,4-tetramethyl-3-thioxocyclobutanone (5)-methylide (69) occur at ca. +45°C and, generally, the products of type 70 were obtained in high yield (36,94,97,130) (Scheme 5.25). Reaction with ( )- and (Z)-configured dipolaro-philes stereospecifically afford trans and cis configured adducts. 

Thio)Kohlensaure-amid-hydrazid-Hydrochloride spalten 2-Amino-l,3,4-oxadiazole zu Koh-lensaure-(2-acyl-hydrazid)-(2-ami nocar bo nyl-hydrazid)-imiden bzw. -(2-acyl-hy-drazid)-[2-(amino-thiocarbonyl)-hydrazid]-imid-Hydrochloriden, die sich z.B. mit 2N Natronlaugc zu 3-(Aminocarbonyl-hydrazino)- bzw. 3-[(Amino-thiocarbonyl)-hydrazino]-l,2,4-triazolen cyclisieren lassen737-784,785 ... 

The condensation of 1,4-diamines with a variety of carboxylic acid derivatives, e.g. imidate esters, orthoformic esters, /V-ethoxycarbonylthioamides (77JOC2530), nitriles and ethoxyacetylene, produces the cyclic amidine linkage —N = C(R)NH— (67AHC(8)2l, p. 40). Cyclic ureas, —NHC(0)NH—, have been similarly produced using carbonyl chloride, A, A -carbonyldi imidazole, carbon monoxide, thiocarbonyl chloride or carbon disulfide (67AHC(8)21, p. 38). 

Thiocarbonyl-A-imides 208 and thiocarbonyl-A-ylides 209 are two unusual classes of sulfur-centered 1,3-dipoles that may be possible candidates as 47r-components for the synthesis of tetrahydro-l,4-(oxa/thia)-2-azoles. Both are unstable transient species that can be trapped by suitable dipolarophiles. 

In CHEC-II(1996), the formation of 1,4,2-dithiazolidine derivatives 212 (R = Ar) from the sterically crowded thione 203 and arylazides (R = Ar) was reported. Nitrogen is evolved from the initially formed thiatriazoline cycloadduct 210 and the in situ-formed thiocarbonyl-A-imide 211 is trapped by the superdipolarophilic thione 203 (Scheme 28) <1996CHEC-II(4)532, 1993HCA2147>. Some new examples of this reaction have appeared. Thus, methyl azidoacetate and the thione 203 afford the corresponding dithiazolidine 212 (R = CH2COOMe)... 

Using a similar approach, through [2+3] dipolar cycloaddition reactions, the syntheses of 532 and 533 were accomplished from thiocarbonyl y-imides 531 and norbornene-3,4-dicarboxylate or /ra r-cycloctene <2000T4231>. 

Zur Herstellung von Thiobenzoesdure- und subst. Thiobenzoesdure-O-ethylestern (74 95%) aus Aryl-nitrilen s.Lit.102. Aus 2,5-Dicyan-pyridin erhalt man fiber das Bis-carbon-saure-methylester-imid das orange 2,5-Bis-(methoxy-thiocarbonyl)-pyridin (50%)1O2a. 

Bei 1 -Thiooxalsaure-2-ethyl-l-O-isopropylester erfolgt mit 1,2-Diamino-benzol Amid-Bil-dung an der Ester-Seite und Kmipfung der Ester-imid-Struktur an der Seite der Isopropyl-oxy-thiocarbonyl-Funktion. 2-Amino-thiophenol cyclisiert innerhalb der Isopropyloxy-thiocarbonyl-Funktion zum 2-Ethoxycarbonyl-l, 3-benzthiazol156. 

In addition to activated olefins, other double-bond substrates, such as carbonyl and thiocarbonyl compounds and azomethines have been used ( ). Likewise, heterocumulenes, such as carbon disulfide, isocyanates, isothiocyanates, carbodiimides, and N-sulfinylamines have been added to nitrile imides ( ). While usually reaction occurs across one of the cumulative double bonds, with carbon disulfide only the bis-adduct LVIII could be isolated ( ). 

Diazoalkanes," azides, " partial oxiranes, oxazolidinone, " aziri-dines, trimethylsilyhnethyltriflate salts (TfO TMSM ), and a-aminoac-id ester imines form pentaatomic rings through reactive intermediate ylides. Species like thiocarbonyl S-ylides, " thiocarbonyl S-imides, thiocar-bonyl S-sulfides (thiosulfines), and thiocarbonyl S-oxides (sulfines) containing a three atomic system as central unit with the sulfur atom in the middle position are known as sulfur centred 1,3-dipoles. Oxiranes react opening the ring by L.A. Thiosulfines, " reactive intermediates in the formation of 1,2,4-trithiolanes, are not isolable species since they decompose to thione and sulfur. 

---