Correction: Stannyl phosphaketene as a synthon for phosphorus analogues of ß-lactams.

Correction for 'Stannyl phosphaketene as a synthon for phosphorus analogues of ß-lactams' by Yong-an Luo et al., Chem. Commun., 2023, https://doi.org/10.1039/d3cc03117a.

Stannyl phosphaketene as a synthon for phosphorus analogues of ß-lactams.

The reaction of the stannyl phosphaketene (Nacnac)SnPCO 1 (Nacnac = CH{(CMe)(2,6-iPr2C6H3N)}2) with B(C6F5)3 produced the 1,4-addition product of (Nacnac)SnPCO(B(C6F5)3). However, the corresponding reactions in the presence of dimethyl maleate, diisopropyl fumarate or diethyl-but-2-ynedioate gave [2+2] addition yielding four-membered phosphacycles, ((Nacnac)Sn(MeO2C))CHPC(OB(C6F5)3)CH(CO2Me), [(C6F5)3B)PC(OSn)C(CO2Me)CH(CO2Me)]2, (Nacnac)Sn(iPrO2C)CC(OAl(C6F5)3)P[CH(CO2iPr)CH2(CO2iPr)]CH(CO2iPr), and (Nacnac)SnP (EtO2CCC(CO2Et))CO(B(C6F5)3), respectively. In contrast, the corresponding reaction of phenylacetylene gave the FLP-addition product (Nacnac)SnOC(P)C(Ph)CH(B(C6F5)3). Collectively, this reactivity demonstrates that the stannyl phosphaketene 1 can act as a synthon for P-analogues of ß-lactam derivatives.

Reactivity of frustrated Lewis pairs with BOC protected diazocarboxylates: FLP capture of diazene.

Reactions of (tBuO2CN)2 with FLPs are examined. B(C6F5)3 interacts with the carbonyl oxygen atoms inducing loss of CH2CMe2; however, in the presence of basic donors, the protons are intercepted affording the salts [Hbase]2 [((C6F5)3BO2CN)2] (base = tBu3P 1, NC5H2Ph32, HNC5H6Me43). In contrast, in the presence of (o-Tol)3P, a proton transfers to the diazo-N atom affording (o-Tol)3PN(CO2tBu)NHB(C6F5)34. Further addition of B(C6F5)3 to 4 prompts loss of olefin CH2CMe2 and CO2 affording (o-Tol)3PNHNHB(C6F5)35. The course of these reactions is examined by extensive DFT calculations. The nature of 5 is consistent with the FLP reduction of a diazene fragment.

Diazene Chemistry: Metal-Free Models of N2 Reduction Intermediates.

Interest in main group chemistry related to the Haber-Bosch process has drawn less attention than that of transition metal species. Herein, we show that the steric demands in (tBuO2CN)2 block initial interaction of B(C6F5)3 with nitrogen and prompt loss of methylpropene and CO2 to diazene (N2H2) borane adduct 1 and the analogous hydrazine (N2H4) adduct 2. These species react with basic phosphines to give anions of 3 and 5 containing N2H and N2H3 fragments, respectively. While these species are not derived directly from N2, they represent metal-free species containing N2Hn (n = 1-4) fragments, which model plausible intermediates in the reduction of N2.

Transient hydroboration and hydroalumination of activated azo-species: avenues to NBO and NAlO-heterobicycles.

Reactions of the boranes, BH(C6F5)2 or 9-BBN, with azodicarboxylates or an azodicarbonylamide provide facile access to NBO heterocyclic compounds. The products [(C6F5)2BOC(X)N]2 X = OEt 1, OiPr 2, OCH2CCl33, OCH2Ph 4, NC5H105) and [(9-BBN)OC(X)N]2 (X = OEt 6, OiPr 7, NC5H108) and [Ph2B)OC(OtBu)N]29 were prepared. In another variation, (nacnac)AlH2 (nacnac = (C6H3iPr2NC(Me))2CH) afforded the Al-heterobicycle [(nacnac)Al(H)OC(OEt)N]210. The mechanism for the formation of these products is proposed to involve transient hydroboration or hydroalumination of the NN double bond.