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The reactions of allenylphosphonates/allenylphosphine oxides or an allenyl sulfone [4-Cl-C6H4-SO2C(R)=C=CMe2] with the aldimine PhCH=NTs in the presence of a carbene [NHC·HCl/DBU] afford tosylated allylic phosphonates/phosphine oxides or a sulfone. This reaction involves C-S bond formation and not C-O bond formation, and thus is different from similar reactions of allenes with PhCH=NTs in the presence of bases like DMAP, DBU or Ph3P/(alkyl)3P wherein cycloaddition products are generally observed. The reactions of phosphorylated allenes with DBU lead to the unprecedented formation of products in which the DBU ring is cleaved, as evidenced by single crystal Xray crystallography. This observation suggests a 'reactant' role for DBU when using this base in the reactions of allenes. [ABSTRACT FROM AUTHOR]

Use of a simple inorganic ring system with the cyclodiphosph(III)azane skeleton [e.g. [(RNH)P-N(t-Bu)]2 [R= t-Bu (7), i-Pr (8)] to probe some of the intermediates proposed in phosphine mediated organic reactions is highlighted. Thus the reaction of 7–8 with the allenylphosphine oxide Ph2P(O)C(Ph)=C=CH2 (9) affords the phosphinimines [(RNH)P(μ-N-t-Bu)2 P(= N-R)-C(=CH2)CH(Ph)-P(O)Ph2] [R = t-Bu (10), i-Pr (11)], while a similar reaction of 7–8 with dimethyl maleate (or dimethyl fumarate) affords the ylides [(RNH)P(μ-N-t-Bu)2 P(NH-R)= C(CO2Me)-CH2(CO2Me) [R = t-Bu (18), i-Pr (19)]. The implication of such reactions on phosphine mediated organic transformations including Morita–Baylis–Hillman reaction is mentioned. In a rather rare type of situation, an unusually long phosphoryl (P=O) bond [1.538 (5) Å] as revealed the X-ray structure of {(R)-6,6′-(t-Bu)2-1,1′-(C10H5)2-2,2′-O2-}{P(O)(N-t-Bu)2-P(Se)} (27) is rationalized by means of crystallographic disorder in packing after comparing the data with that in the literature and {1,1′-(C10H6)2-2,2′-O2}{P(Se)(N-t-Bu)2-P(Se)} (29). X-ray structures of the new compounds 10–11, 18–19, 27 and 29 are discussed. Compound 10 crystallizes in the chiral space group Pca2(1) with (S)-chirality at the carbon center [–C( =CH2)CH(Ph)-P] suggesting a case of spontaneous resolution through crystallization. [ABSTRACT FROM AUTHOR]

We have described the first example of an umpolung strategy for intermolecular [2 + 2 + 1] cycloaddition between two aryl aldehydes and a nitrile under the influence of TMSOTf that proceeds through the formation of N-C, O-C and C-C bonds providing a simple synthetic protocol for obtaining 2,4,5-trisubstituted oxazoles., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

A rhodium-catalyzed decarbonylative aerobic oxidation of cyclic α-diketones has been developed for the first time, where the regioselective formations of α-pyrones and isocoumarins have been achieved. The current decarbonylative aerobic oxidation pathway proceeds via the C-C bond cleavage followed by a C-O bond formation, representing a biomimetic oxidation approach to unsaturated six-membered cyclic lactones. The unique ability of rhodium catalysts to induce the decarbonylative aerobic oxidation opens up a new synthetic toolbox that utilizes the "regioselective single carbon" extrusion strategy.