New bimolecular mechanistic pathway for 1,3-hydrogen shift in allenamide and allene system: A theoretical prediction

Allenamides: A Powerful and Versatile Building Block in Organic Synthesis

“…This 1,3-H shift was found to be highly regio- and stereoselective, as products 581 were obtained with >20:1 E/Z ratios. It is noteworthy that related 1,3-H shift has been documented by others 78,152b (also see Scheme 69). Recently, Das 152c reported a computational study on such 1,3-H shift.…”

“…It is noteworthy that related 1,3-H shift has been documented by others 78,152b (also see Scheme 69). Recently, Das 152c reported a computational study on such 1,3-H shift. Details of their study will not be discussed here.…”

“…The thermal 1,3-H shift required higher temperatures and/or longer reaction times than those of α-isomerizations. It is noteworthy again that related isomerization or 1,3-H shift from the γ-position has been documented by others 25,52,111,152b (see Schemes 11, 19, and 107). …”

“…Hsung 152a reported a series of studies on regio- and stereoselective isomerizations of allenamides with first of which leading to the preparation of de novo 2-amido-dienes and a tandem isomerization-6 p -electron electrocyclic ring-closure (Scheme 160). It was found that under either thermal conditions (condition A) or Brønsted acidic conditions (condition B), allenamides 580 underwent effective isomerization, or 1,3-H shift, to give de novo 2-amido-dienes 581 .…”

“…Hsung 152a also examined isomerizations or 1,3-H shift of allenamides from the γ-position for the preparation of 1-amido-dienes (Scheme 166). Authors found that 1,3-H shift of two types of γ-substituted allenamides with a cyclohexylidene group 605 and those with an iso-propylidene group 607 led to 1-amidodienes 606 or 608 , respectively, as E -enamides exclusively.…”