01176nas a2200169   4500008004100000022001400041245014500055210006900200260000900269300001400278490000700292520050300299100002600802700002600828700002200854856013000876       2021                        eng d  a1477-052000aBismuth(iii)-catalyzed bis-cyclization of propargylic diol-esters: a unified approach for the synthesis of [5,5]- and [6,5]-oxaspirolactones0 aBismuthiiicatalyzed biscyclization of propargylic diolesters a u  cAUG   a6618-66220 v193 aHerein we disclose an unprecedented intramolecular cascade strategy for the construction of alpha,beta-unsaturated [5,5]- and [6,5]-oxaspirolactones that capitalizes on the pi-electrophilic Lewis acid-catalyzed 5-exo-dig or 6-exo-dig mode of cyclization of propargylic diol esters, followed by dehydration and spirolactonization steps. Moreover, semi-protected substrates also delivered the respective oxaspirolactones with the same ease and in appreciable yields under optimal reaction conditions.1 aKambale, Digambar, A.1 aBorade, Balasaheb, R.1 aKontham, Ravindar  uhttps://library.ncl.res.in/content/bismuthiii-catalyzed-bis-cyclization-propargylic-diol-esters-unified-approach-synthesis-55