lithium;benzenethiol;4-(2-bromoethylidene)oxane;chloroform;dichloromethane;ethyl 2-amino-4-(oxan-4-ylidene)butanoate;ethyl 2-(benzhydrylideneamino)acetate;ethyl 2-(benzhydrylideneamino)-4-(oxan-4-ylidene)butanoate;ethyl 1-[(2S)-2-(methoxycarbonylamino)-3-methylbutanoyl]-8-oxa-1-azaspiro[4.5]decane-2-carboxylate;ethyl 2-[(4-nitrophenyl)sulfonylamino]-4-(oxan-4-ylidene)butanoate;ethyl 1-(4-nitrophenyl)sulfonyl-8-oxa-1-azaspiro[4.5]decane-2-carboxylate;ethyl 8-oxa-1-azaspiro[4.5]decane-2-carboxylate;1-[(2S)-2-(methoxycarbonylamino)-3-methylbutanoyl]-8-oxa-1-azaspiro[4.5]decane-2-carboxylic acid;methyl (3S)-3-carbonochloridoyl-4-methylpentanoate;1-nitro-4-sulfochloranuidylbenzene;trifluoromethanesulfonic acid;hydroxide