Alkylthio esters

Carbonsauren 144-154,157f, 560, 571, 599f unges. 81 f, 154-157 a-Alkylthio- -ester 564 -amide 230-244, 599 Amino- 161-165 2-Amino- 663 -anhydride 174-180, 526 -azide 263f. 

Mitchell has reported that benzyl a-chlorobenzyl sulfides are cleanly converted into stilbenes on successive treatment with PPhs and Bu OK (Scheme 13). Desulfurization of an intermediate thiirane by PPh3 is a likely pathway for this reaction. Benzyl a,a-dichlorobenzyl sulfides are converted into diphe-nylacetylenes under the same conditions." Viehe has reported that pyrolysis of ot-halo-a-alkylthio esters, ketones and nitriles under reduced pressure furnishes a,p-unsaturated esters, ketones and nitriles respectively it is probable that these reactions also take place via intermediate thiiranes. a-Chlorophenacyl phenacyl sulfide is converted into ( )-dibenzoylethylene on treatment with EtsN. ... 

PhjSbO mediates the dehydrative condensation of carboxylic acids with amines via Ph3Sb(OCOR)2 as reactive intermediates [146]. This catalytic system has been applied to dipeptide synthesis (Scheme 14.73) [147]. Treatment of olefins with a mixture of AcOH and P4S10 in the presence of Ph jSbO affords alkylthio esters [148]. 

Very intense-smeUing sulfur compounds with low thresholds of perception often act as key aromatic compounds. They often have very similar structures and contain an important odorophore (a group responsible for the odour character), which is sulfur and oxygen in positions 1 and 3 of the molecule (8-120). This structure occurs in mercaptans, thioacetals, mercapto ethers, mer-capto ketones, alkylthio esters and other compounds listed in the following sections. 

It is estimated that mote than 25 x 10 different potentially toxic OP esters can be made using Schrader s classic (27) formula for effective phosphorylating agents, (39), where R and are short-chain alkyl, alkoxy, alkylthio, or alkylamino groups, and X is a displaceable moiety with a high energy P-bond such as E or acyl anhydride, and the pentavalent phosphoms atom is bonded to oxygen or sulfur. 

Amongst miscellaneous UV spectra recorded are those of alkylthio adducts of pyrido[3,2-c]pyridazine (78KGS1272), various pyrido[3,4-d]pyridazines (57AC(R)728) and several vinyl-pyridine-azodicarboxylic ester adducts (79T2027, 79KGS639). 

Ring expansion of haloalkyloxiranes provides a simple two-step procedure for the preparation of azetidin-3-ols (Section 5.09.2.3.2(f)) which can be extended to include 3-substituted ethers and O-esters (79CRV331 p. 341). The availability of 3-hydroxyazetidines provides access to a variety of 3-substituted azetidines, including halogeno, amino and alkylthio derivatives, by further substitution reactions (Section 5.09.2.2.4). Photolysis of phenylacylamines has also found application in the formation of azetidin-3-ols (33). Not surprisingly, few 2-0-substituted azetidines are known. The 2-methoxyazetidine (57) has been produced by an internal displacement, where the internal amide ion is generated by nucleophilic addition to an imine. 

Haloacetyl groups have also a synthetic potential. Thus, pesticidal (alkylthio)-vinyl esters of phosphorus acid derivatives have been prepared by the introduction and subsequent displacement of two chlorine atoms in the acetyl moiety attached to the furazan ring (Scheme 69) [73GEP(0)2144393]. 

Rh2(OAc)4 has become the catalyst of choice for insertion of carbene moieties into the N—H bond of (3-lactams. Two cases of intermolecular reaction have been reported. The carbene unit derived from alkyl aryldiazoacetates 322 seems to be inserted only into the ring N—H bond of 323 246). Similarly, N-malonyl- 3-lactams 327 are available from diazomalonic esters 325 and (3-lactams 326 297). If, however, the acetate function in 326 is replaced by an alkylthio or arylthio group, C/S insertion rather than N/H insertion takes place (see Sect. 7.2). Reaction of ethyl diazoacetoacetate 57b with 328 also yields an N/H insertion product (329) 298>, rather than ethyl l-aza-4-oxa-3-methyl-7-oxabicyclo[3.2.0]hex-2-ene-2-earboxylate, as had been claimed before 299). 

Yoneda, S., Kawase, T., and Yoshida, Z.-i., Synthesis of [l-(alkylthio)]- and (1-mercapto)cycloalkanephosphonic esters by the reactions of cycloalkaneth-iones with trialkyl phosphites, /. Org. Chem., 43, 1980, 1978. 

In addition to 1,2-alkyl shifts, sulfonium ylides with P-hydrogen can also undergo fragmentation into an olefin and a thioether [1317,1318]. When allylic thioethers are treated with two equivalents of ethyl diazoacetate in the presence of a catalyst for diazodecomposition, S-alkylation and elimination of the thioalkyl group from the initially formed a-alkylthio-4-alkenoic esters occurs to yield 2,4-dienoic esters [1319]. 

Thiokohlensaure-benzoylimid-S-ester bzw. Dithiokohlensaure-benzoylimid-ester setzen sich mit Hydroxylamin in methanolischer Losung nach liingerer Reaktionszeit zu 3-AIkoxy-5-phenyl- bzw. 3-Alkylthio-5-phenyl-1,2,4-oxadiazolen um175 ... 

Sulfenylation and Selenylation of Ketones and Carboxylic Esters Alkylthio-de-hydrogenation, etc. 

---