Kak-Shan Shia

Reductive cleavage of benzyl ethers with lithium naphthalenide. A convenient method for debenzylation

Abstract An operationally simple, high-yielding and highly chemoselective procedure has been developed for the conversion of benzyl ethers to the corresponding alcohols, using lithium naphthalenide as the reagent.

Lithium naphthalenide induced reductive alkylation of α-cyano ketones. A general method for regiocontrol of α, α-dialkylation of ketones

Abstract An efficient general method for the consecutive introduction of two alkyl groups to the α carbon of a ketone carbonyl has been developed, making use of the lithium naphthalenide induced reductive alkylation of an α-cyano ketone system as a key operation.

A convenient new procedure for the construction of highly substituted acetates. Reductive alkylation of α-cyano esters

Abstract A convenient, highly efficient general method for the preparation of highly substituted acetates has been developed, making use of reductive alkylation of α-cyano esters as a key operation.

An improved general synthetic approach to cis-clerodane diterpenoids. A more efficient total synthesis of (±)-6β-acetoxy-2-oxokolavenool

Abstract The previously developed general synthetic approach to cis -clerodane diterpenoids has been greatly improved using 4-(2-benzyloxy)ethyl-2-cyano-4-methyl-2,5-cyclohexadien-1-one ( 4 ) as the starting dienophile. This approach allows the direct incorporation of an angular methyl group via reductive alkylation of the α-cyano ketone system. The viability of this approach to cis -clerodanes has been demonstrated in the alternative total synthesis of (±)-6β-acetoxy-2-oxokolavenool ( 1 ).

Palladium(II) acetate mediated oxidative cyclization of ω-unsaturated α-cyano ketones. A facile methylenecyclopentane annulation process

A highly efficient methylenecyclopentane annulation process has been developed based on the Pd(II)-mediated oxidative cyclization of ω-unsaturated α-cyano ketones, readily accessed via the Michael addition of 3-butenylmagnesium bromide with 2-cyano-2-cycloalkenones.

The first total synthesis of xenitorins B and C: assignment of absolute configuration

Starting from (-)-beta-pinene, the first total synthesis of xenitorins B and C has been accomplished, which also allowed the assignment of their absolute configuration.

Application of the Barton photochemical reaction in the synthesis of 1-dethia-3-aza-1-carba-2-oxacephem: a novel agent against resistant pathogenic microorganisms.

Racemic 7-(phenylacetamido)-1-dethia-3-aza-1-carba-2-oxacephem 3 was synthesized and found to possess antibacterial activity against Staphylococcus aureus FDA 209P, Escherichia coli ATCC 39188, Pseudomonas aeruginosa 1101-75 and Klebsiella pneumoniae NCTC 418 as well as the beta-lactamase producing organisms E. coli A9675 and P. aeruginosa 18S-H and the methicillin-resistant organism S. aureus 95. Formation of the carbacephem 3 originated from the Barton photochemical reaction in the conversion of 8 to 10. Intramolecular cyclization of syn-oximino beta-lactam 10 afforded 7-azido-2-oxa-3-azacephem 11, which was reduced and acylated to 12. Enzymatic removal of the methyl group from 12 gave the target molecule 3.

Reductive alkylation of α-cyano ketones induced by samarium iodide

SmI2-HMPA was shown to be an effective reagent for reductive alkylation of α-cyano ketones, a useful process for regiocontrol of α,α-dialkylation of ketones.

A facile two-carbon ring expansion process based on the 2-cyano-1-vinylcycloalkanol system

Abstract Upon exposure to potassium hydride in THF in the presence of 18-crown-6, several 2-cyano-1-vinylcycloalkanol derivatives were found to undergo ring enlargement to give the corresponding γ-cyano cycloalkanones in synthetically useful yields.

Diels–Alder chemistry of 2-cyanoalk-2-enones. A convenient general approach to angularly substituted polycyclic systems

Under zinc chloride catalysis, a number of 2-cyanoalk-2-enones nrepresenting various ring sizes were found to undergo facile cycloaddition nwith several selected conjugated dienes; sequential treatment of the nadducts with lithium naphthalenide and an alkylating agent resulted in the ndirect replacement of the angular cyano group with an alkyl group, nproviding easy access to angularly substituted polycyclic systems.