2 research outputs found
Selective Isomerization–Hydroformylation Sequence: A Strategy to Valuable α‑Methyl-Branched Aldehydes from Terminal Olefins
For
the first time, an original selective isomerization-hydroformylation
sequence to convert terminal olefins bearing an anionic moiety to
α-methyl-branched aldehydes with unprecedented selectivities
is reported. This opens up new synthetic avenues to these valuable
building blocks from inexpensive and bioavailable substrates. The
catalytic system involves a suitable selective monoisomerization catalyst
and a selective supramolecular catalyst that preorganizes a substrate
molecule prior to the hydroformylation reaction via hydrogen bonding.
In principle, the strategy can be extended to other classes of substrates,
providing suitable catalysts for the hydroformylation of internal
alkenes
Mono‑, Di‑, and Triborylphosphine Analogues of Triarylphosphines
Diazaborinylphosphines
based on the 1,8-diaminonaphthylboronamide
heterocycle are prepared by a chlorosilane-elimination reaction, and
their structural and bonding properties are compared to those of PPh<sub>3</sub>. The precursor chloroborane ClBÂ{1,8-(NH)<sub>2</sub>C<sub>10</sub>H<sub>6</sub>} (<b>I</b>) is fully characterized including
its crystal structure, which features intermolecular π–π
stacking, B···N interactions, and N–H···Cl
hydrogen bonding. Treatment of <b>I</b> with Ph<sub>3–<i>n</i></sub>PÂ(SiMe<sub>3</sub>)<sub><i>n</i></sub> gave
the corresponding Ph<sub>3–<i>n</i></sub>PÂ(BÂ{1,8-(NH)<sub>2</sub>C<sub>10</sub>H<sub>6</sub>})<sub><i>n</i></sub>, {<b>L</b><sub><b>1</b></sub> (<i>n</i> =
1), <b>L</b><sub><b>2</b></sub> (<i>n</i> =
2), and <b>L</b><sub><b>3</b></sub> (<i>n</i> = 3)}. The crystal structures of <b>L</b><sub><b>1</b>–<b>3</b></sub> reveal an increase in the planarity
at P as a function of <i>n</i>, and the steric bulk of the
diazaborinyl substituent BÂ{1,8-(NH)<sub>2</sub>C<sub>10</sub>H<sub>6</sub>} is similar to that of a phenyl. Nucleus-independent chemical
shift calculations were carried out that suggest that the 14 π-electron
diazaborinyl substituent can be described as aromatic overall, though
the BN<sub>2</sub>-containing ring is slightly antiaromatic. The complexes <i>cis-</i>[MoÂ(<b>L</b><sub><b>1</b>–<b>3</b></sub>)<sub>2</sub>(CO)<sub>4</sub>] (<b>1</b>–<b>3</b>) are prepared from [MoÂ(nbd)Â(CO)<sub>4</sub>] (nbd = norbornadiene)
and <b>L</b><sub><b>1</b>–<b>3</b></sub>.
From the position of the νÂ(CO) (<i>A</i><sub>1</sub>) band in the IR spectra of <b>1</b>–<b>3</b>,
it is deduced that the diazaborinyl substituent has a donating capacity
similar to an alkyl group