Esters phenylthiomethyl

LM Siemens, FW Rottnek, LS Trzupek. Selective catalysis of ester aminolysis. An approach to peptide active esters, (phenylthiomethyl esters). J Org Chem 55, 3507,... 

Q -Phenylthiomethyl-jS-hydroxy esters (50) can be prepared, predominantly as the iyn-isomer, by a stereoselective one-pot Michael-aldol tandem reaction. The seleno analogue can similarly be prepared (again, mainly syn), using PhSeLi in diethyl ether, but phenoxide ion is not sufficiently reactive for this sequence. 

Esters of A -(phenylthiomethyl)AAs undergo a base (NaH)-promoted addition to unsaturated esters to give a mixture of diastereroisomeric regioi-somers (Scheme 9) (84TL1579). 

We have just seen in a preceding scheme (see Section 4.2.1.5) an example of alkylation of a silylated enolate with phenylthiomethyl chloride. The Lewis acid-promoted phenylthioalkylation of O-silylated enolates of ketones, aldehydes, esters and lactones has been used by Paterson and Fleming as a convenient synthetic route to a-alkylated or alkylidenated carbonyl compounds [323-325] according to the accompanying scheme. 

O-allylester-O.O-diethylester XII/2, 627 -O-allylester-O-methylester-S-phenylthiomethyl-ester XII/2, 658... 

Other Reactions at the Carbonyl Carbon Atom.—A new method for converting ketones into methylene compounds is claimed to be successful even in cases where the Wittig and related reactions fail. Treatment of the ketone (e.g. 271) with phenylthiomethyl-lithium (270) gives a derivative (272), which may be acetylated or benzoylated in situ. Reduction of the ester (273) with lithium-NH3 gives the methylene compound (274) in good yield. The conversion of cholest-5-en-3-one into 3-methylenecholest-5-ene contrasts with the lability of the 5-en-3-one to the basic conditions required for the Wittig reaction. Even many hindered ketones appear to be reactive. 

Synonyms 0,0-diethyl-5 -p-chlorophenyl-thiomethyl dithiophosphate 5-(4-chloro-phenylthiomethyl)diethylphosphorothiolo-thionate S- ((( -chlorophenyl)thio)me-thyl)-C),C)-dietyl phosphorodithioate phos-phorodithioic acid 5-(((p-chlorophenyl) thio)methyl)-0,C)- diethyl ester Trithion Hexathion... 

Tsuji reported a total synthesis of zearalenone using Pd-catalyzed carbonylation. In this total synthesis, they synthesized the key compound by Pd-catalyzed carbonylation. The reacion of l-iodo-2-phenylthiomethyl-4,6-dimethoxybenzene 3 (Scheme 7) with 10-iodo-6,2 -[l,3]dioxolane-2-decanol 4 was carried out under carbon monoxide (12 atm) to afford the corresponding m-iodoalkyl ester of 2-phenylthiomethy 1-4,6-dimethoxybenzene 5. 

An older route to (a-iodoalkyl)boronic esters involved preparation of pinacol (phenylthiomethyl)boronate (149), which could be deprotonated and die resulting anion alkylated by alkyl hahdes [80]. The phenylthio group can be replaced with iodo by treatment with methyl iodide and sodium iodide in acetonitrile. This route can only yield racemic (a-iodoalkyl)boronic esters, but it has been revived for preparation of... 

However, solution-phase model studies indicated that C3 hydroxyl of 96 was sterically shielded owing to the neighboring (5)-(phenylthiomethyl)benzyl ether. Therefore, the auxiliary of 94 was converted into acetyl ester (95) by treatment with acetic anhydride in the presence of BF3-OEt2. Removal of Alloc in 95 under standard conditions provided glycosyl acceptor 96, which was coupled with preactivated B to form resin-bound trisaccharide 97. Finally, the required target 98 was achieved after performing few more stereoselective additional reactions. 

Similarly, the conjugated addition of thiolate derivatives to a,p-unsaturated ester 63a in the presence of chiral N-sulfinimines 64 afforded a-phenylthiomethyl-p-... 

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