Thionyl chloride mediated

Details of the sequence of steps in the thionyl chloride-mediated transformation of 4-carboxy-3,4-dihydro-3-phenyl-l(2//)-isoquinolines into indeno[l,2-c]isoquinolones have been elucidated62 and it is confirmed that the dehydrogenation precedes the electrophilic cyclization [of (56)]. 

A novel synthetic approach was developed by R.E. Taylor et al. for the preparation of the triene portion of the biologically active polyketide apoptolidin. The allylic chloride substrate was prepared from an allylic alcohol via a thionyl chloride mediated rearrangement. Next, the allylic chloride was subjected to the Ganem oxidation by treating it with five equivalents of trimethylamine A/-oxide (TMANO) in DMSO at room temperature to obtain the desired a,p-unsaturated aldehyde. Interestingly, the original Kornblum oxidation conditions were not well suited for this system because of the required high reaction temperature. 

Surface-mediated addition of HC1 or HBr can be carried out in the presence of silica or alumina.150 The hydrogen halides can be generated from thionyl chloride, oxalyl chloride, oxalyl bromide, phosphorus tribromide, or acetyl bromide. The kinetic products from HC1 and 1-phenylpropyne result from syn addition, but isomerization to the more stable Z-isomer occurs upon continued exposure to the acidic conditions. 

In the preparation of iodides, but not bromides, PMHS may be substituted for the TMDO. Chlorides can be obtained if thionyl chloride and zinc iodide are added to suppress the formation of symmetrical ethers.314 An example of this type of reductive chlorination is shown by the TMDO-mediated conversion of p-tolualdehyde into p-methylbenzyl chloride (Eq. 201).313 To obtain chlorides from aldehydes having electron-withdrawing groups such as nitro or carbomethoxy, the initial reaction is first carried out at —70° and the mixture is then heated to reflux in order to reduce the formation of symmetrical ether by-products. Zinc chloride is substituted for zinc iodide for the synthesis of chlorides of substrates with electron-donating groups such as methoxy and hydroxy.314... 

The most widely used method for the preparation of 1,3,2-dioxathiolane. Y-oxides (cyclic sulfites) 65 bearing C-linked substituents is the reaction of the corresponding 1,2-diols with thionyl chloride in presence of pyridine or Et3N (Scheme 18). More reactive 1,3,2-dioxathiolane. Y,.Y-dioxidcs (cyclic sulfates) 66 are usually obtained by oxidation of sulfites 65 with sodium periodate, which is mediated by mthenium tetroxide generated in situ from a catalytic amount of ruthenium trichloride. Numerous derivatives 65 and 66 were obtained via this approach and its modifications for further transformations, mostly as the synthetic equivalents of epoxides <1997AHC89, 2000T7051> (see also Sections 6.05.5 and 6.05.6, and Tables 1-7). 

The synthesis of benzomorphans substituted in the 11-position from a 2-tetralone (Scheme 4.2, p. 157) involves either thionyl chloride dehydration of an 11-methylcarbinol (13a)(9) or a pyrolysis of the corresponding acetate perchlorate (136)methylene derivative (14). Carbocation-mediated processes in bridged compounds of this type are likely to give rearrangement byproducts. Kugita and Takeda(124) isolated from the thionyl chloride route an unstable chloride (203), and the indenotetrahydropyridine (204). Other reports(30 96a,125) of unidentified products from these reactions resulted in an investigation 126 127 of both pathways (Scheme 4.20). 

Reactions, which are seemingly 1,3-sigmatropic rearrangements, have been carried out with various substrates. Cyclopropyl vinyl alcohols have been converted to 3-cyclopropylprop-2-enyl derivatives by treatment with acetic acid, ° pyridinium chlorochromate, thionyl chloride,benzenethiol, and diethylaminosulfur trifluoride, e.g. reaction of 3 with thionyl chloride to give Double bond migration has also been mediated by treatment... 

The reaction of surface carboxyl groups can lead to either esters or amides. The first step in both cases is to generate acid chlorides on the diamond surface by treating it with thionyl chloride. This intermediate then can easily be reacted with the respective alcohols or amines. In this manner it has been possible, for instance, to estabhsh on a diamond film a thymidine ester that could be cormected to a strand of DNA in a subsequent Ugase-mediated reaction (Figure 6.44). Hydroxyl... 

A later optimized synthesis also starts from the 1,4-diols. They are then converted into cyclic sulfates with thionyl chloride on mediation of ruthenium chloride and sodium periodate. The sulfates are transformed with dili-thiumbis(phosphido)ethane into bis(phospho-lano)ethane (BPE) ligands or with dilithium-... 

In general, only slight modifications to the Amdt-Eistert homologation have been reported. As mentioned previously, classically two equivalents of diazomethane are required due to the production of HCl upon reaction of diazomethane with the acid chloride. Newmann and Beal reported a modification whereby triethylamine is added to capture the released HCl and therefore only one equivalent of diazomethane is required. Another major source of diversity in the reported Amdt-Eistert reactions is in the initial activation of the carboxylic acid. While thionyl chloride is classically used, other reagents that mediate the eonversion of a earboxylic acid to an acid chloride are equally suitable. As reported above, alternative activation methods such as the formation of mixed anhydrides and acyl mesylates are also be applicable. 

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