title: N-(Fluoren-9-ylmethoxy-carbon-yl)-l-isoleucine.
abstract: In the crystal structure of the title compound [systematic name fluoren-9-ylmethyl N-(1-carb-oxy-2-methyl-butyl)carbamate], C(21)H(23)NO(4), the mol-ecular plane of the O=C-NH-C(α) unit is slightly pyramidalized. The N atom deviates from the basal plane by 0.2086 (12) Å. The O=C-N-C(α) torsion angle is -17.2 (2)°, and the C-N and O=C bond lengths are 1.3675 (17) and 1.2122 (17) Å, respectively. Apparently the character of the sp(2) hybrids of the mol-ecular plane is, to some extent, reduced. The crystal structure exhibits two inter-molecular hydrogen bonds (O-H⋯O and N-H⋯O), in which the hydr-oxy O atom acts as a donor to the carbonyl group and an acceptor of the amide group, respectively.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yamada
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hashizume
authors.forename: Tadashi
authors.initials: T
authors.lastname: Shimizu
authors.forename: Kenzo
authors.initials: K
authors.lastname: Deguchi