137909-97-8

Upstream product

• 139732-48-2 3,6-dihydrothiopyran 4-(trimethylsilyloxy)-2H-thiopyran 
• 1072-72-6 Tetrahydrothiopyran-4-one 
• 100-52-7 benzaldehyde 
• 137909-97-8 (S)-3-((S)-Hydroxy-phenyl-methyl)-tetrahydro-thiopyran-4-one 

Downstream Products

• 137909-97-8 (S)-3-((R)-Hydroxy-phenyl-methyl)-tetrahydro-thiopyran-4-one 
• 137909-93-4 (1SR,2SR,3RS)-2-methyl-1-phenylpentane-1,3-diol 
• 137909-92-3 (3R,4S)-3-((R)-Hydroxy-phenyl-methyl)-tetrahydro-thiopyran-4-ol 

Relevant academic research and scientific papers

The thiopyran route to polypropionates revisited: Selective syn and anti aldol reactions via 3,6-dihydro-4-trimethylsilyloxy-2H-thiopyran

Aldol reaction of the amine free Li enolate of tetrahydro-4H-thiopyran-4-one with 1,4-dioxa-8-thi aspiro[4.5]decane-6-carboxaldehyde gives mainly the 2,3-anti-3,4-syn aldol (7:1) in good yield; reaction of the LDA generated lithium enolate proceeds poorly. Using the trimethylsilyl enol ether and TiCl4 gives the 2,3-syn-3,4-syn aldol (>10:1). The adducts can be used for polypropionate synthesis.

Syn-anti isomerization of aldols by enolization

A variety of aldol adducts are shown to undergo efficient syn-anti isomerization in the presence of imidazole by an enolization mechanism. Isomerizations are high yielding and occur with little or none of the usual byproducts arising from competing elimination or retroaldol reactions. Most substrates reach equilibrium within 0.3-3 days at ambient temperature in chloroform, benzene, or dichloromethane containing 0.3-1 M imidazole. The process is particularly facile for aldols derived from tetrahydro-4H-thiopyran- 4-one with rate constants for equilibration varying over ca. 1 order of magnitude for the adducts studied; structurally related aldols derived from cyclohexanone isomerized ca. 3-4 times slower. Isomerization of the acyclic aldol 5-hydroxy-4-methyl-5-phenyl-3-pentanone required heating to 60 °C but was achieved with minimal (A methoxymethyl ether derivative isomerized 30-40 times slower than the parent aldol. Isomerization of α,α′-disubstituted aldols and α,α′-bisaldols indicated low regioselectivity in the enolization. The synthetic utility of the process was demonstrated with the effective preparation of aldol stereoisomers unobtainable by direct methods.

Highly diastereoselective aldol reactions of 4-thianone: A new strategy for synthesis of polypropionate frames

The aldol reactions of the lithium enolate of 4-thianone with aldehydes yield the threo-isomers of aldols in a highly stereoselective manner and also showed high diastereoface selectivity. Other metal enolates of this reagent exhibited different behabiors