Solvent-free microwave-assisted Meyers’ lactamization

Does gastric dilation predict adverse perinatal or surgical outcome in fetuses with gastroschisis?

“…5 The most general method for their synthesis, introduced in the seminal work by Meyers et al.,1, 2 wherein a γ‐ketoacid is condensed with an amino alcohol under dehydrating conditions in toluene, heated to reflux, is still, by far, the most commonly employed means of accessing the bicyclic scaffold B . Modifications have been made to the Meyers’ lactamization with the aim of introducing milder conditions;6 these modifications range from using microwave energy6a or employing Lewis acid catalysis,6b to activating the acid 6c. A second commonly employed,7 but stepwise, route to these bicyclic lactams, also originating from the Meyers’ group,2a relies heavily on N ‐acyliminium chemistry, which has been extensively elucidated by Speckamp and Hiemstra 8.…”

Studies on the Regioselectivity of the Cyclization of Tryptophanol‐Derived Oxazolopiperidone Lactams

“…Under the usual reaction conditions (toluene, reflux), a mixture of 6 and its 8a‐epimer (80 % yield, 87:13 ratio) was obtained 15. A more convenient experimental procedure involved the use of microwave16 irradiation of an equimolecular mixture of the starting materials (10 min at 110 °C), which provided a 92:8 diastereoisomeric mixture of 6 and its 8a‐epimer in 77 % yield, with only traces of the cyclized product 9 (see Scheme ) being detected.…”

Microwaves in Heterocyclic Chemistry

“…Deprez-Poulain and co-workers reported the preparation of Meyer's chiral lactam from (R)-phenylglycinol with various γ -keto acids [Eq. (16.5)] using solventless reaction conditions [30]. High diastereoselectivity was achieved by application of microwave irradiation in a short reaction time.…”