Download PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... A high yielding synthesis of variously substituted 2,3-dihydro-1H-spiro[isoquinoline-4,4′-piperidine] is reported. N-(2-nitrophenyl)sulfonyl was successfully used as both an activating and protecting group for the key Pictet–Spengler reaction. ... The privileged structure 1-(methylsulfonyl)- ...