Ca(CF3COO)2: An efficient Lewis acid catalyst for chemo- and regio-selective enamination of β-dicarbonyl compounds

One-pot synthesis of an indole-substituted 7,8-dicarba-nido-dodecahydroundecaborate(-1)

Carbaboranes are increasingly used as pharmacophores to replace phenyl substituents in established drug molecules. In contrast to traditional organic chemistry, elaborate procedures to introduce functionality frequently fail in the case of carbaboranes and their chemistry is often hampered by degradation of the cluster. Herein, the development of a one-pot synthesis of a water-soluble N-nido-dicarbaborato indole is presented, including a proposed mechanism for the reaction sequence. These studies provide useful synthetic tools for the conjugation of two important pharmacophores, indoles and carbaboranes.

Crystal structure of (1S,2R,4S)-1-[(morpholin-4-yl)meth-yl]-4-(prop-1-en-2-yl)cyclo-hexane-1,2-diol

Besides intra­molecular O—H⋯N hydrogen bonds, the crystal structure displays inter­molecular O—H⋯O and C—H⋯O hydrogen bonds linking the mol­ecules into undulating layers parallel to the (01) plane.

The asymmetric unit of the title compound, C₁₄H₂₅NO₃, contains two independent mol­ecules with similar geometry. The morpholine and cyclo­hexane rings of both mol­ecules adopt a chair conformation. Intra­molecular O—H⋯N hydrogen bonds are observed. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds into chains parallel to the [101] direction. The chains are further connected through C—H⋯O hydrogen bonds forming undulating layers parallel to the (-101) plane. The absolute configuration was assigned by reference to an unchanging chiral centre in the synthetic procedure.

(2Z,2′Z)-Diethyl 3,3′-[butane-1,4-diylbis(azanediyl)]bis(but-2-enoate)

The whole mol­ecule of the title β-enamino­ester, C₁₆H₂₈N₂O₄, is generated by a crystallographic inversion center, situated at the mid-point of the central C—C bond of the 1,4-diamino­butane segment. There are two intra­molecular N—H⋯O hydrogen bonds that generate S(6) ring motifs. This leads to the Z conformation about the C=C bonds [1.3756 (17) Å]. The mol­ecule is S-shaped with the planar central 1,4-diamino­butane segment [maximum deviation for non H-atoms = 0.0058 (13) Å] being inclined to the ethyl butyl­enonate fragment [C—C—O—C—C=C—C; maximum deviation = 0.0710 (12) Å] by 15.56 (10)°. In the crystal, mol­ecules are linked via C—H⋯O inter­actions, leading to the formation of an undulating two-dimensional network lying parallel to the bc plane.

Efficient synthesis of β-enaminones and β-enaminoesters catalyzed by gold (I)/silver (I) under solvent-free conditions

An efficient method for the synthesis of β-enaminones and β-enaminoesters using a combination of [(PPh(3))AuCl]/AgOTf as catalyst has been developed. The reaction between 1,3-dicarbonyl compounds and primary amines was carried out under solvent-free conditions with low catalyst loading in good to excellent yields at room temperature.

(Z)-4-(2-Naphthyl-amino)-pent-3-en-2-one

The title compound, C(15)H(15)NO, which was synthesized under solvent-free conditions by the reaction of acetoacetone and 2-naphthyl-amine, adopts a Z conformation about the C=C bond. The enamine-ketone fragment is approximately planar [maximum deviation = 0.026 (3) Å] and forms a dihedral angle of 39.78 (3)° with the naphthalene ring system. An intra-molecular N-H⋯O hydrogen bond is observed.

rac-Ethyl (2Z)-3-{2-[(Z)-4-eth-oxy-4-oxobut-2-en-2-yl-amino]-cyclo-hexyl-amino}-but-2-enoate

The asymmetric unit of the title compound, C(18)H(30)N(2)O(4), contains two independent mol-ecules. In each mol-ecule, the cyclo-hexane ring adopts a chair conformation with equatorial orientation of the substituents, and the conformation is stabilized by two intra-molecular N-H⋯O hydrogen bonds, forming rings of S(6) graph-set motif. One eth-oxy group and one ethyl group are disordered over two sets of sites with refined occupancy ratios of 0.704 (2):0.296 (2) and 0.505 (3):0.495 (3), respectively. In the crystal, a weak inter-molecular C-H⋯O hydrogen inter-action is observed, involving the O atom of the major component of the disordered eth-oxy group.

(1S,2R,4S)-1-[(Benzyl-amino)-meth-yl]-4-(prop-1-en-2-yl)cyclo-hexane-1,2-diol

The title compound, C₁₇H₂₅NO₂, was synthesized by epoxidation of the double bond of (S)-perillyl alcohol [(S)-4-isopropenyl-1-cyclo­hexenyl­methanol], followed by the oxirane ring-opening by benzyl­amine using [Ca(CF₃CO₂)₂] as catalyst under solvent-free condition at 313 K. The mol­ecular conformation is stabilized by an intra­molecular O—H⋯N hydrogen bond. In the crystal, mol­ecules are linked by inter­molecular N—H⋯O hydrogen bonds, forming chains parallel to the a axis, which are further connected by O—H⋯O hydrogen bonds into sheets parallel to (010). The absolute configuration of the mol­ecule is known from the synthetic procedure.