Towards routine organic structure determination using Raman microscopy.

Raman microscopy can reveal a compound-specific vibrational "fingerprint" from micrograms of material with no sample preparation. We expect this increasingly available instrumentation to routinely assist synthetic chemists in structure determination; however, interpreting the information-dense spectra can be challenging for unreported compounds. Appropriate theoretical calculations using the highly efficient r2SCAN-3c method can accurately predict peak positions but are less precise in matching peak heights. To limit incorrect biases while comparing experimental and theoretical spectra, we introduce a user-friendly software that gives a match score to assist with structure determination. The capabilities and limitations of this approach are demonstrated for several proof-of-concept examples including the characterization of intermediates in the total synthesis of deoxyaspidodispermine.

Synthesis and characterization of novel conformers of (E)-2-(3-nitro-H-imidazo[1,2-a]pyridin-2-ylthio)-N'-benzylideneacetohydrazide derivatives.

Eighteen new N-acylhydrazones (9a-r) containing the imidazo[1,2-a]pyridine scaffold were synthesized through a seven steps reaction sequence, ending with a condensation of 2-(3-nitro-H-imidazo[1,2-a]pyridin-2-ylthio)acetohydrazide with various benzaldehyde derivatives (8a-r). All synthesized compounds were characterized by 1D NMR (1 H and 13 C NMR) and 2D NMR (NOESY) spectroscopic analyses and high-resolution mass spectrometry (HRMS). The analysis of 1 H NMR data performed at room temperature in deuterated dimethylsulfoxide (DMSO-d6 ) revealed the presence of (E)-2-(3-nitro-H-imidazo[1,2-a]pyridin-2-ylthio)-N'-benzylideneacetohydrazide (9a-r) as a mixture of two conformers, namely, syn-periplanar E (sp E) and anti-periplanar E (ap E). For all N-acylhydrazones that were synthesized, the sp E conformer was found to be the major form except in the case of hydrazone derived from o-hydroxybenzaldehyde.

Synthesis of Deoxyaspidodispermine Based on a Functional Protecting Group Strategy.

A synthesis of deoxyaspidodispermine was produced from homotyramine. This approach is based on the application of a functional protecting group strategy that not only masks the reactivity of sensitive groups during crucial steps but also possesses a moiety desired in the final target, which is transferred to the substrate at the time of deprotection. This synthesis highlights an aza-Michael-Smiles ring-closure cascade, which enables the formation of a tetracyclic system from a nosylamide protecting group.

Elaboration of Functionalized Organophosphates.

In this study, the rapid transformation of inexpensive phenols into polyfunctionalized cyclohexenones containing a phosphonate in one pot is described. Such systems readily obtained from simple aromatic compounds could open up a multitude of synthetic possibilities. For example, this scaffold was easily and stereoselectively transformed into the corresponding enol functionality in the same pot by the addition of sodium borohydride.