Thiono ethers

The same thing can be done for primary and secondary R by treating alkyl chloro-formates (ROCOCl) with tri-n-propylsilane in the presence of fert-butyl peroxide and by treating thiono ethers ROC(=S)W (where W can be OAr or other... 

This is a valuable procedure because medium and large ring ethers are not easily made, while the corresponding thiono lactones can be prepared from the readily available lactones (see, e.g., 10-23) by Reaction 16-10. 

Ring expansion of thiono lactones (cyclic ethers)... 

Wohler143 first described the formation, from concentrated aqueous thiocyanic acid, of a compound, C2H2N2S3 later named isoperthiocyanic acid, and now formulated as 3-imino-5-thiono-l,2,4-dithia-zolidine (144). Solutions of isoperthiocyanic acid in alkali deposit sulfur this redissolves presently giving a liquid containing144-147 the salt of an isomeric acid, later named perthiocyanic acid, for which the 3,5-dimercapto-l,2,4-thiadiazole structure is now accepted (see Section III, J, 1). This acid, isolated from its barium salt by treatment with mineral acid and ether extraction,144,145 readily reverts to isoperthiocyanic acid,144 but fairly stable specimens are obtainable under carefully controlled conditions.148 148... 

Thiono esters RCSOR can be reduced to ethers RCH2OR with Raney nickel (14-27). " Reaction of thio esters, such as C—0C(=0)Ph with Ph2SiH2 and Ph3SnH with BEt3, followed by AIBN (p. 935) leads to reduction of the C=S unit to give an ether. " " Since the thiono esters can be prepared from carboxylic... 

PhjSnH-AIBN in toluene (10 examples, 72-99%). Accordingly, a two-step conversion of esters and lactones to ethers via thionoesters/lactones can be achieved on this basis. 2-Thiono-l,3-dioxolanes are similarly desulfurized to give the dioxolanes, therefore diols can be protected in the form of heterocycles which are acid-stable but eventually switched to acid-sensitive entities. 

Thiono esters and lactones are converted to ethers by PhiSiHi and catalytic Ph,SnH, Et,B. Partial dechlorination of polychloroarenes with triethylsilane and a homogeneous Rh-phosphine catalyst proceeds in high yields. -... 

Thiono esters and lactones are important intermediates in modern organic synthesis since they easily undergo useful follow-up reactions. Ethers are formed on reduction with Raney nickel or... 

A stirred soln. of ethyl -anilinocrotonate in ether allowed to react 2 hrs. at room temp, with p-nitrobenzoyl isothiocyanate ethyl 6-methyl-2-p-nitro-phenyl-l-phenyl-4-thiono-5-pyrimidinecarboxylate. Y 77%. F. e. and limitations s. G. de Stevens, B. Smolinsky, and L. Dorfman, J. Org. Ghem. 29, 1115 (1964). 

Oishi and his co-workers have reported that aromatic thiono-esters (408), in the presence of boron trifluoride ethyl-etherate, rearrange to the corresponding thiolo-esters (409). The disappearance of the thiono-ester took place in accordance with first-order kinetics, and electron-donating para-substituents were found to accelerate the conversion, which was characterized by the Hammett p value of -1.38. The mechanism of the rearrangement was considered to involve the intermediate (410), in agreement with the results of cross-over experiments. The thermal rearrangement of thioaroyl thiocyanates (411) to thioaroyl isothiocyanates (412) was also found to be influenced by substituents. Thiono-ester-thiolo-ester... 

The photochemistry of thiono-esters has been studied quite extensively in the past. Rungwerth and Schwetlick pointed out that, besides forming enediol ethers when sulphur is eliminated or yielding olefins in Norrish Type... 

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