Ir-catalyzed C–H borylation is found to be compatible with Boc protecting groups. Thus, pyrroles, indoles, and azaindoles can be selectively functionalized at C–H positions β to N. The Boc group can be removed on thermolysis or left intact during subsequent transformations.

Substituted α-alkoxysilanes can be deprotonated by alkyllithium bases and made to undergo Wittig rearrangements to afford the #x0005B;1,4]- and [1,2]-rearranged products in varying ratios. Substitution at the benzylic migrating carbon and/or at the allylic carbon of the allyl moiety impacts the rearrangement reaction, influencing the reactivity as well as the [1,4]-/[1,2]-selectivity. Diastereomeric α-alkoxysilanes show different reactivities with the syn diastereomer being the more reactive isomer.

Biocatalytic process-development continues to advance toward discovering alternative transformation reactions to synthesize fine chemicals. Here, a 5-methylidene-3,5dihydro-4H-imidazol-4-one (MIO)-dependent phenylalanine aminomutase from Taxus canadensis (TcPAM) was repurposed to irreversibly biocatalyze an intermolecular amine transfer reaction that converted ring-substituted transcinnamate epoxide racemates to their corresponding arylserines. From among 12 substrates, the aminomutase ringopened 3′-Cl-cinnamate epoxide to 3′-Cl-phenylserine 140 times faster than it opened the 4′-Cl-isomer, which was turned over slowest among all epoxides tested. GC/MS analysis of chiral auxiliary derivatives of the biocatalyzed phenylserine analogues showed that the TcPAM-transamination reaction opened the epoxides enantio-and diastereoselectively. Each product mixture contained (2S)+(2R)-anti (erythro) and ( 2S)+(2R)-syn (threo) pairs with the anti-isomers predominating (∼90:10 dr). Integrating the vicinal proton signals in the 1 H NMR spectrum of the enzyme-catalyzed phenylserines and calculating the chemical shift difference (Δδ) between the anti and syn proton signals confirmed the diastereomeric ratios and relative stereochemistries. Application of a (2S)-threonine aldolase from E. coli further established the absolute stereochemistry of the chiral derivatives of the diastereomeric enzymatically derived products. The 2R:2S ratio for the biocatalyzed anti-isomers was highest (88:12) for 3′-NO 2 -phenylserine and lowest (66:34) for 4′-Fphenylserine. This showed that the stereospecificity of TcPAM is in part directed by the substituent-type on the cinnamate epoxide analogue. The catalyst also converted each cinnamate epoxide analogue to its corresponding isoserine, highlighting a biocatalytic route to arylisoserines, which play a key role in building the pharmacophore seen in anticancer and protease inhibitor drugs.

The compound 1-octen-3-ol is a known attractant of some mosquito species, which has led to the hypothesis that olfactory stimulation by this alkenol may be associated with the following structural elements: a terminal site of unsaturation or high electron density; a structural capability for hydrogen bonding, e.g., -OH, -NH2, NHR, NR2, etc.; a saturated hydrocarbon chain of a certain minimum length; and a certain relative distance between the region of high electron density and the alcohol (or other hydrogen-bonding) functional group. Using this logic, we synthesized 20 alkenol analogs based on the octenol double-bonded carbon skeleton. The attraction of female Aedes albopictus and Culex quinquefasciatus to these analogs was compared with 1-octen-3-ol as a standard in semi-field trials. For both species, collections from Mosquito Magnet-X (MMX) suction traps baited with the alkenol analogs in the absence of carbon dioxide were not significantly different from octenol-only baited traps, with the exception of (Z)-3-hepten-1-ol which collected significantly more Ae. albopictus. In the presence of CO2, most of the collections from traps baited with an alkenol were considerably increased for both species but not different from octenol plus CO2, with the exception of Ae. albopictus where (Z)-3-decen-1-ol, (Z)-4-hexen-1-ol, 7-octen-2-ol, and 8-nonen-3-ol significantly depressed trap catches. Although no clearly identifiable structure-activity relationship could be determined from our collected data, we did find that MMX traps baited with carbon dioxide and 4-penten-2-ol or (E)-2-decen-4-ol significantly enhanced Cx. quinquefasciatus collections up to nearly 3-fold compared with octenol plus carbon dioxide.

alpha-Benzyloxyallylsilane undergoes efficient [1,4]-Wittig rearrangement to generate an enolate intermediate that can be trapped with various electrophiles, thereby providing a new synthetic approach to substituted acylsilanes.