Three-component coupling reaction and cyclization of N-tosylimines and TMS-substituted propiolate mediated by DABCO

A new three-component coupling reaction of methyl 3-trimethylsilylpropiolate, N-tosylimine, and tosylamide mediated by DABCO was developed. This reaction was based on the consecutive alpha- and beta-activation method of propiolate involving intramolecular silyl migration previously developed by our group. On the basis of these results, a new cyclization reaction was designed to find a chromene-forming reaction utilizing salicyl N-tosylimine as a bifunctional substrate.     

Enantioselective syntheses of (-)- and (+)-monomorine I

A concise enantioselective total synthesis of unnatural (-)-monomorine I has been achieved starting from lactam 2 in 54% overall yield. Natural (+)-monomorine I was also synthesized.     

Transition metal-catalyzed asymmetric reactions using P-chirogenic diaminophosphine oxides: DIAPHOXs

This review describes the development of a new class of chiral phosphorus ligands: amino acid-derived P-chirogenic diaminophosphine oxides, DIAPHOXs, and their application to several transition metal-catalyzed asymmetric allylic substitution reactions. Pd-catalyzed asymmetric allylic alkylation with cyclic beta-keto esters as prochiral nucleophiles was initially examined using P-chirogenic diaminophosphine oxide 1a, resulting in highly enantioselective construction of quaternary stereocenters. Mechanistic investigations revealed that 1a is activated by N,O-bis(trimethylsilyl)acetamide-induced tautomerization to afford a trivalent diamidophosphite species 13, which functions as the actual ligand. Pd-catalyzed asymmetric allylic substitutions of both acyclic and cyclic substrates were also examined using various nucleophiles such as malonate derivatives, nitromethane, aliphatic amines, and aromatic amines, providing a variety of chiral compounds with good to excellent enantioselectivity. In addition, Ir-catalyzed asymmetric allylic amination and alkylation of terminal allylic carbonates were examined using structurally optimized P-chirogenic diaminophosphine oxides, and the corresponding branched products were obtained in a highly regio- and enantioselective manner. Furthermore, the developed catalytic asymmetric process was successfully applied to the catalytic enantioselective synthesis of biologically active compounds, (R)-preclamol, (R)-baclofen hydrochloride, and (-)-paroxetine.     

A note on the independence of premiss rule

In this note, we prove that certain theories of (many‐sorted) intuitionistic predicate logic are closed under the independence of premiss rule (IPR). As corollaries, we show that and extended by some non‐classical axioms and non‐constructive axioms are closed under IPR.     

Pd-catalyzed asymmetric allylic substitution reactions using P-chirogenic diaminophosphine oxides: DIAPHOXs

This paper describes the development of a new class of chiral phosphorus ligand: aspartic acid-derived P-chirogenic diaminophosphine oxides, DIAPHOXs, and their application to several Pd-catalyzed asymmetric allylic substitution reactions. Pd-catalyzed asymmetric allylic alkylation was initially examined in detail using diaminophosphine oxides 1a, resulting in the highly enantioselective construction of quaternary stereocenters. Mechanistic investigations revealed that 1a is activated by N,O-bis(trimethylsilyl)acetamide-induced tautomerization to afford a trivalent diamidophosphite species 12, which functions as the actual ligand. Furthermore, asymmetric allylic amination was examined using Pd-DIAPHOX catalyst systems, providing a variety of chiral allylic amines.     

Ir-catalyzed asymmetric allylic alkylation using chiral diaminophosphine oxides: DIAPHOXs. Formal enantioselective synthesis of (−)-paroxetine

An Ir-catalyzed asymmetric allylic alkylation using chiral diaminophosphine oxide is described. Asymmetric allylic alkylation of terminal allylic carbonates proceeded using 5 mol % of Ir catalyst, 5 mol % of DIAPHOX 1i, 10 mol % of NaPF₆, 10 mol % of LiOAc, and N,O-bis(trimethylsilyl)acetamide (BSA), affording the corresponding branched products in excellent yield and in up to 95% ee. The developed catalytic asymmetric reaction was successfully applied to a formal enantioselective synthesis of (−)-paroxetine.     

Highly stereoselective construction of 4,6-cis-substituted quinolizidine ring core: an application to enantioselective total synthesis of the marine alkaloid clavepictines A, B and pictamine

The enantioselective total synthesis of the marine alkaloids clavepictines A, B and pictamine has been achieved through the highly stereocontrolled quinolizidine ring closure of the conformationally constrained piperidine ring system (2), which bears the chiral centers and appropriate functionality needed for the synthesis of target alkaloids. The absolute stereochemistry of clavepictines and pictamine was verified to be 3R, 4S, 6S, 9aS by the present synthesis.     

Cyclic carbonates,novel expandable monomers on polymerization

A variety of cyclic carbonates was shown to undergo volume expansion on polymerization. The degree of volume expansion, which was measured by the density gradient tube method, was ranging from 1.1% to 7.7%. The volume expansion was examined by assuming a change in molecular interaction such as dipole moment between monomer and polymer states.