Di-tert-butyl Ethynylimidodicarbonate as a General Synthon for the β-Aminoethylation of Organic Electrophiles: Application to the Formal Synthesis of Pyrrolidinoindoline Alkaloids (±)-CPC-1 and (±)-Alline

Synthesis and Reactivity of a Terminal 1-Alkynyl Triazene

1-Alkynyl triazenes are versatile reagents in synthetic organic chemistry, but the structural diversity of this compound class has so far been limited. Herein, we describe the synthesis of a terminal 1-alkynyl triazene. Subsequent functionalization allows the preparation of 1-alkynyl triazenes with a range of functional groups including esters, alcohols, cyanides, phosphonates, and amides. Furthermore, the terminal 1-alkynyl triazene can be used for the synthesis of di- and triynes and for the preparation of (hetero)aromatic triazenes in metal-catalyzed cyclization reactions.

Synthesis of 1-Deoxymannojirimycin from d-Fructose using the Mitsunobu Reaction

Three different Mitsunobu reactions have been investigated for the synthesis of 1-deoxymannojirimycin (1-DMJ) from d-fructose. The highest yielding and most practical synthesis can be undertaken on a 10 g scale with minimal chromatography. In the key step, N,O-di-Boc-hydroxylamine reacts with methyl 1,3-isopropylidene-α-d-fructofuranose under Mitsunobu conditions to give 14. Acidic hydrolysis affords nitrone 15, which reduces quantitatively via catalytic hydrogenolysis to afford 1-DMJ (4) in 55% overall yield from d-fructose (cf. 37% for azide route and 29% for nosyl route).

Copper-Catalyzed Alkynylation of Hydrazides: An Easy Access to Functionalized Azadipeptides

We report a copper-catalyzed alkynylation of azadipeptides using ethynylbenziodoxolone (EBX) reagents. Nonsymmetrical ynehydrazides could be obtained in 25-97% yield using azaglycine derivatives as nucleophiles. The transformation is compatible with most functional groups naturally occurring on amino acid side chains and allows the transfer of silyl-, alkyl-, and aryl-substituted alkynes. The obtained α-alkynyl azaglycine products could be further functionalized by nucleophilic attack or cycloaddition on the triple bond.