Asymmetric Total Synthesis of Vincadifformine Enabled by a Thiourea-Phosphonium Salt Catalyzed Mannich-Type Reaction.

An asymmetric total synthesis of vincadifformine is described. The limited tactics with chiral cation-directed catalysis in total synthesis inspired the development of our strategy for accessing this alkaloid in enantionrich form. The route features a thiourea-phosphonium salt catalyzed Mannich-type reaction, a phosphine-promoted aza-Morita-Baylis-Hillman reaction and a trifluoroacetic acid promoted deprotection/amidation cascade process.

Aniline-containing guests recognized by α,α',δ,δ'-tetramethyl-cucurbit[6]uril host.

The host-guest complexation of symmetrical α,α',δ,δ'-tetramethyl-cucurbit[6]uril (TMeQ[6]) and cucurbit[7]uril (Q[7]) with a series of aniline-containing guests has been investigated by various experimental techniques including NMR, ITC, and X-ray crystallography. Experimental results indicate that both TMeQ[6] and Q[7] hosts can encapsulate aniline-containing guests to form stable inclusion complexes. However, the oval cavity of TMeQ[6] is more complementary in size and shape to the aromatic ring of the guests than the spherical cavity of Q[7].

Host-guest complexation of di-cyclohexanocucurbit[6]uril and hexa-cyclohexanocucurbit[6]uril with alkyldiammonium ions: a comparative study.

The host-guest complexation of symmetrical di-cyclohexanocucurbit[6]uril (Cy2Q[6]) and hexa-cyclohexanocucurbit[6]uril (Cy6Q[6]) with a series of alkyldiammonium ions (H(3+)N(CH(2))nNH(3+), n = 2-8) has been studied both in solution and in the gas phase. (1)H NMR data indicate that all alkyldiammonium ions have inclusion interactions with both hosts except for the ethanediammonium ion. In addition, if the alkyl chain of the alkyldiammonium ion is longer than n = 5 methylene groups, compressed conformation may occur, which depends on the cavity shape of the hosts and the length of the alkyl chain.

Kinetic resolution of primary allylic amines via palladium-catalyzed asymmetric allylic alkylation of malononitriles.

A range of primary allylic amines were resolved with selectivity factors of up to 491 through [Pd(allyl)Cl]2/(S)-BINAP-catalyzed and mesitylsulfonyl hydrazide-accelerated asymmetric allylic alkylation of malononitriles involving enantioselective C-N bond cleavage under aerobic conditions. Moreover, the reaction proved useful for the asymmetric synthesis of α-branched allyl-substituted malononitriles with high enantiopurity.