Setelah pengusirannya dari Partai Komunis, Syrtsov terjun ke pekerjaan ekonomi, mengelola pabrik amunisi.<ref name=Pankov /> InPada antanggal unknownyang datetidak diketahui, hedia joinedbergabung adengan secretkelompok oppositionoposisi grouprahasia withdengan [[Vissarion Lominadze|Lominadze]] as well asserta [[Jan Sten]]. ThisKelompok groupini thenkemudian joinedbergabung adengan largeraliansi conspiratorialkonspirasi allianceyang inlebih besar pada tahun 1932 withdengan [[Leon Trotsky]], zinovievists anddan some unnamedbeberapa [[RightOposisi OppositionKanan|rightistskaum kanan]].Inyang atidak letterdisebutkan fromnamanya. Dalam surat dari [[Lev Sedov|Trotsky'sputra sonTrotsky]], theymereka weredisebut referredsebagai to'kelompok as the 'Sten–Lominadze group'. [[Pierre Broué]] wrotemenulis thatbahwa theblok bloctersebut mostkemungkinan likelybesar dissolveddibubarkan inpada earlyawal tahun 1933, becausekarena somebeberapa ofanggotanya itsditangkap membersdan wereKamenev arrestedserta andZinoviev Kamenevtelah andbergabung Zinovievkembali had joineddengan Stalin again.<ref>{{Cite web|title=Pierre Broué: The "Bloc" of the Oppositions against Stalin (January 1980)|url=https://www.marxists.org/archive/broue/1980/01/bloc.html|access-date=2020-08-07|website=www.marxists.org}}</ref>
Syrtsov was arrested on 19 April 1937 during the [[Great Purge]]. Following protracted interrogation he was sentenced to death on 10 September 1937 and executed in Moscow that same day.<ref name=Zhertvy>{{cite web|url=http://lists.memo.ru/index18.htm |title=Жертвы политического террора в СССР |publisher=Lists.memo.ru |accessdate=2013-06-12}}</ref>
