In(OTf)3-catalyzed tandem aza-Piancatelli rearrangement/Michael reaction for the synthesis of 3,4-dihydro-2H-benzo[b][1,4]thiazine and oxazine derivatives

Aza‐Piancatelli Cyclization as a Platform for the Preparation of Scaffolds of Natural Compounds: Application to the Total Synthesis of Bruceolline D

“…To fulfil this goal, we prepared an aniline derivative incorporating a furan moiety ( 7g ), which is a well‐established diene system for Diels‐Alder processes. To our surprise, in contrast with precedent reports,[13i], [13k] we did not obtain the classic Diels‐Alder adduct, forming instead tetrahydro‐1 H ‐indene 14 in 90 % yield in HFIP (Scheme ). This reactivity was also extended to 1,3‐dienes to furnish the corresponding skeleton 15 in good yield (65 %) under identical reaction conditions.…”

“…Since the pioneering work of Denisov et al and Read de Alaniz group, we and others have directed our efforts towards the preparation of even more densely functionalized targets using the aza‐Piancatelli cyclization as a cornerstone as well as the development of enantioselective versions. [13h], [13k], In our case, we implemented new strategies for the synthesis of polycyclic structures such as cyclopenta[ b ]pyrroles, cyclopenta[ b ]piperazinones[13g] and tetrahydrobenzo[ b ]azepines[13j] by pairing the aza‐Piancatelli cyclization with a second key transformation, such as hydroamination, annulation or Michael addition. In turn, the studies related to the influence of the substitution pattern at the positions C3 and C4 of the furan ring on the reactivity have been limited.…”

“…In turn, the studies related to the influence of the substitution pattern at the positions C3 and C4 of the furan ring on the reactivity have been limited. [13e], [13f], [13g], This issue is particularly critical when considering the compounds mentioned above, which bear a multitude of additional functional groups, including heteroatoms on the cyclopentane ring. As a result, the question remains whether the aza‐Piancatelli cyclization could be useful for the synthesis of natural products .…”

Synthesis and Applications of Stenhouse Salts and Derivatives

“…Reactionscope of the Indium-catalyzed formation of tricyclic CPs 312-322. [43] Chem.E ur.J. 2018, 24,9170 -9186 www.chemeurj.org sponding colorless hydrophilic zwitterionic CP 344 [45,46] upon irradiationw ith wavelengths spanning from 450 to 750 nm, depending on the amine moiety.…”

“…In 2012, Reddy and co‐workers described the preparation of thiazine and oxazin CP derivatives 312 – 322 via the In(OTf) 3 ‐catalyzed domino aza‐Piancatelli rearrangement/Michael addition (Scheme ) . It is noteworthy that elimination of the amine to reestablish the α,β‐unsaturated ketone was not observed.…”