01484nas a2200181   4500008004100000022001400041245012600055210006900181260000800250300001400258490000700272520079700279100002501076700002401101700002601125700002201151856012901173       2024                        eng d  a1523-706000aReady access to [5,6,5]-Trioxa-spiro and fused ketals via ag-catalyzed cascade annulation of 4-pentyn-1-ols and aldehydes0 aReady access to 565Trioxaspiro and fused ketals via agcatalyzed   cAUG  a7116-71210 v263 a<p>
	In this study, we unveil the versatility of 4-pentyn-1-ols as carbonyl surrogates for the unprecedented synthesis of diverse oxygen heterocycles, including [5,6,5]-bis-spiroketals (trioxadispiroketals) and [5,6,5]-furano-spiroketals related to bioactive natural products. These reactions commence with the pi-activation-induced intramolecular hydroalkoxylation of 4-pentyn-1-ols, yielding cyclic enol ethers, which undergo subsequent three-component annulation with aldehydes in a [2+2+1+1] fashion, resulting in the formation of [5,6,5]-bis-spiroketals. Notably, the distinctive steric features of alkynyl alcohols, particularly those with a secondary or tertiary alcohol functionality, dictate divergent reaction pathways, leading to the formation of [5,6,5]-furano-spiroketals.</p>
1 aVinodkumar, Ramavath1 aNakate, Ashwini, K.1 aGamidi, Rama, Krishna1 aKontham, Ravindar  uhttps://library.ncl.res.in/content/ready-access-565-trioxa-spiro-and-fused-ketals-ag-catalyzed-cascade-annulation-4-pentyn-1