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C‐acylimines are generally obtained through condensation/dehydration of simple and readily available glyoxals and amines. The structure resembles naturally occurring biological substances due to the presence of the imino group (−N=C−). Chemically, C‐acylimines exhibit ambiphilic reactivity, and hence, their synthetic chemistry becomes more attractive and viable for the synthesis of various aza‐cyclic/heterocyclic compounds, including their asymmetric counterpart. Therefore, many synthetic methodologies were developed from these readily preparable C‐acylimines. Surprisingly, there is no account/review available on this specific topic. Hence we present here an account of all the synthetic endeavours developed from C‐acylimines to synthesize small molecules and complex systems using various strategies. [ABSTRACT FROM AUTHOR]

The chemical reactivity descriptors have been calculated through Molecular Electron Density Theory encompassing Conceptual DFT. The validity of "Koopmans' theorem in DFT" (KID) has been assessed by a comparison between the global descriptors (electronegativity, total hardness, and global electrophilicity) calculated through vertical energy values and those arising from the HOMO and LUMO values. These results suggest that the KID procedure is valid and may be used, in conjunction with the B3LYP/3-611G(d, p) level of theory in further studies of related compounds in the aqueous medium. The active sites for nucleophilic and electrophilic attacks have been identified and verified using the local reactivity descriptors: the dual descriptor, the electrophilic and nucleophilic Parr functions, the local reactivity difference index Rk and MEP maps. Obtained results suggest that the antioxidant/antiradical power of investigated compounds may be explained by the highest ambiphilic activation of the oxygen atoms of the hydroxyl groups in the ene-diol moiety. [ABSTRACT FROM AUTHOR]

Deprotonation of [(cAAC)BH2(CN)] provided clean access to the stable boryl anion, [(cAAC)BH(CN)]−. Whereas the addition of soft electrophiles occurred at the nucleophilic boron center, harder silyl electrophiles added to the harder terminal cyano nitrogen. The resulting [(cAAC)BH(CNSiPh3)] species behaved like a silylium boryl nucleophile as well as a neutral silylisonitrile borylene. [ABSTRACT FROM AUTHOR]

The concept of frustrated Lewis pairs (FLPs) has received considerable attention of late, and numerous reports have demonstrated the power of non- or weakly interacting Lewis acid–base pairs for the cooperative activation of small molecules. Although most studies have focused on the use of organic or main-group FLPs that utilize steric encumbrance to prevent adduct formation, a related strategy can be envisioned for both organic and inorganic complexes, in which "electronic frustration" engenders reactivity consistent with both nucleophilic (basic) and electrophilic (acidic) character. Here we propose that such a description is consistent with the behavior of many coordinatively unsaturated transition-metal species featuring metal–ligand multiple bonds, and we further demonstrate that the resultant reactivity may be a powerful tool for the functionalization of C–H and E–H bonds.

Abstract: The reactions of the trimethylsiloxychlorosilanes (Me3SiO)RR′SiCl (1a–h: R′=Ph, 1a: R=H, 1b: R=Me, 1c: R=Et, 1d: R= i Pr, 1e: R= t Bu, 1f: R=Ph, 1g: R=2,4,6-Me3C6H2 (Mes), 1h: R=2,4,6-(Me2CH)3C6H2 (Tip); 1i: R=R′=Mes) with lithium metal in tetrahydrofuran (THF) at −78°C and in a mixture of THF/diethyl ether/n-pentane in a volume ratio 4:1:1 at −110°C lead to mixtures of numerous compounds. Dependent on the substituents silyllithium derivatives (Me3SiO)RR′SiLi (2b–i), Me3SiO(RR′Si)2Li (3a–g), Me3SiRR′SiLi (4a–h), (LiO)RR′SiLi (12e, 12g–i), trisiloxanes (Me3SiO)2SiRR′ (5a–i) and trimethylsiloxydisilanes (6f ∗, 6h ∗, 6i ∗) are formed. All silyllithium compounds were trapped with Me3SiCl or HMe2SiCl resulting in the following products: (Me3SiO)RR′SiSiMe2R″ (6b–i: R″=Me, 7c–i: R″=H), Me3SiO(RR′Si)2SiMe2R″ (8a–g: R″=Me, 9a–g: R″=H), Me3SiRR′SiSiMe2R″ (10a–h: R″=Me, 11a–h: R″=H) and (HMe2SiO)RR′SiSiMe2H (13e, 13g–i). The stability of trimethylsiloxysilyllithiums 2 depends on the substituents and on the temperature. (Me3SiO)Mes2SiLi (2i) is the most stable compound due to the high steric shielding of the silicon centre. The trimethylsiloxysilyllithiums 2a–g undergo partially self-condensation to afford the corresponding trimethylsiloxydisilanyllithiums Me3SiO(RR′Si)2Li (3a–g). (Me3)Si–O bond cleavage was observed for 2e and 2g–i. The relatively stable trimethylsiloxysilyllithiums 2f, 2g and 2i react with n-butyllithium under nucleophilic butylation to give the n-butyl-substituted silyllithiums n BuRR′SiLi (15g, 15f, 15i), which were trapped with Me3SiCl. By reaction of 2g and 2i with 2,3-dimethylbuta-1,3-diene the corresponding 1,1-diarylsilacyclopentenes 17g and 17i are obtained. X-ray studies of 17g revealed a folded silacyclopentene ring with the silicon atom located 0.5Å above the mean plane formed by the four carbon ring atoms. [Copyright &y& Elsevier]

• The methods of NPA, LOL, ACID, CDD were examined to probe the origin of the chameleonic reactivity on the carbyne carbon atoms. • The thermodynamics and kinetics of the nucleophilic reactivity of cyclic conjugated complexes were investigated by DFT calculations. • The ring strain, aromaticity, and the phosphonium substituent determine the ambiphilicity of the same carbyne carbon. Ambiphilic reactivity is a fascinating topic in chemical reactions, attracting considerable interest because ambiphilic reagents can display properties of both nucleophilicity and electrophilicity. However, most of the previous attentions have been focused on the characterization of the ambiphilic reactivity, whereas the origin is less understood. Here we carry out thorough density functional theory (DFT) calculations to probe the origin of the ambiphilic reactivity of the carbyne atom in osmapentalynes, observed previously in experiment. A series of osmium carbyne complexes ranging from acyclic to cyclic, non-conjugated to conjugated, non-aromatic to aromatic, unsubstituted to substituted were designed for comparable studies. Our results indicate that the origin of ambiphilic reactivity in osmapentalyne complexes should be attributed to an interplay of ring strain, aromaticity, and phosphonium substituent. [Display omitted] [ABSTRACT FROM AUTHOR]