Remote Stereochemistry of a Frustrated Lewis Pair Provides Thermal and Photochemical Control of Reactivity.

Hydroboration of tBuC≡CSR with (C6F5)2BH generate the B/S FLPs, (C6F5)2B(RS)C═CH( tBu) (R = ptol, Me). For R = ptol the product Z-1 exhibits Z stereochemistry, is monomeric in solution and is capable of both classical Lewis acid-base and FLP reactivity. Photoisomerization of Z-1 affords E-1, which features an intramolecular S-B interaction promoted by the remote steric influence of the tert-butyl group. E-1 is not active as an FLP under ambient conditions but reacts with phenylacetylene when activated with either heat or light. The stereochemical outcome of the product is dependent on the stimulus employed.

Catalytic double hydroarylation of alkynes to 9,9-disubstituted 9,10-dihydroacridine derivatives by an electrophilic phenoxyphosphonium dication.

The electrophilic pyridinium-substituted phenoxy-phosphonium dicationic salt [(PhO)P(2-(N-Mepy))Ph2][B(C6F5)4]2, is shown to be an effective catalyst for the double hydroarylation of alkynes with diarylamines to afford a series of 9-methyl-9-aryl-9,10-dihydroacridine and 9,10-dimethyl-9-aryl-9,10-dihydroacridine derivatives.

PNPCB heterocycles via thermal and Lewis acid catalyzed trans-hydroborations.

The compounds iPr2P(BH3)N3, tBu2PC[triple bond, length as m-dash]CR (R = Ph , tBu , Cy ) and Ph2PC[triple bond, length as m-dash]CR (R = Ph , tBu , Cy ) were reacted to give the products tBu2P(C[triple bond, length as m-dash]CR)NP(BH3)iPr2 (R = Ph , tBu , Cy ) and Ph2P(C[triple bond, length as m-dash]CR)NP(BH3)iPr2 (R = Ph , tBu , Cy ). Subsequent thermally induced or Lewis acid catalyzed intramolecular hydroboration of and afforded the PNPCB heterocyclic compounds Ph2P(C[double bond, length as m-dash]CHPh)NP(BH2)iPr2 and tBu2P(C[double bond, length as m-dash]CHPh)NP(BH2)iPr2, respectively. Compounds and were crystallographically characterized and the mechanisms and implications for the synthesis of inorganic heterocycles are considered.

Cyclic bent allene hydrido-carbonyl complexes of ruthenium: highly active catalysts for hydrogenation of olefins.

A new family of ruthenium complexes bearing the carbodicarbene-type ligand "cyclic bent allene" (CBA) have been synthesized from the common precursor RuHCl(CO)(PPh3)3. Complexes were evaluated for catalytic activity in the room-temperature hydrogenation of unactivated olefins and were found to be significantly more active than known ruthenium hydrido-carbonyl phosphine or NHC complexes. In particular, RuH(OSO2CF3)(CO)(SIMes)(CBA) was found to be among the most active hydrogenation catalysts, achieving comparable activity to Crabtree's catalyst in the hydrogenation of unactivated trisubstituted olefins and superior activity in the hydrogenation of styrene derivatives in side-by-side catalytic runs. RuH(OSO2CF3)(CO)(SIMes)(CBA) was also found to be highly active in olefin selective hydrogenation in the presence of a variety of unsaturated functional groups, and can achieve exceptional diastereoselectivity in functional-group-directed hydrogenations at very low catalyst loadings.