Using direct infusion electrospray ionization mass and tandem mass spectrometric experiments [ESI-MS(/MS)], we have performed on-line monitoring of some reactions used to form Tröger's bases. Key intermediates, either as cationic species or as protonated forms of neutral species, have been intercepted and characterized. The role of urotropine as the methylene source in these reactions has also been accessed. Reaction pathways shown by ESI-MS(/MS) have been probed by gas-phase ion/molecule reactions, and an expanded mechanism for Tröger's base formation based on the mass spectrometric data has been elaborated.

No abstract

The Baylis-Hillman reaction with chiral a-amino aldehydes has been revisited. The reaction carried out under the influence of ultrasound avoids the aldehyde racemization almost completely, providing useful chiral substrates which can be used as starting materials for the synthesis of natural products. To demonstrate the synthetic applicability of these adducts, the easy preparation of a bicyclic lactam with an indolizidinic skeleton was accomplished.

No abstract

No abstract