Acetylene Derivatives from a Fragmentation Reaction

Abstract

Ba3Nz/BaBrz and Ba,N2/BaIz were examined. On fusing BaBr2 and Ba metal in a molar ratio of 1 : 3 in the presence of nitrogen, a black lustrous product was obtained, which was identified as a hitherto unknown compound, Ba2NBr. It is distinguished by a melting point maximum at 920 "C in the phase diagram of the system Ba3NzlBaBr2. The two eutectics are at 19 mole-% Ba3N2 and 6 10 "C and at 87 mole-% Ba3N2 and 828 "C. In the phase diagram of the Ba3NdBalz system, there is only one melting point maximum, viz. at 10 mole-% Ba3N2 and 81OoC, with accompanying eutectics at 2 mole-"/, Ba3N2 and 692 "C and at 20 mole-% Ba3N2 and 660 "C. A product with 10 mole-% Ba3N2 crystallizes as pale yellow, matted, fine needles and displays characteristic X-ray interference patterns which indicate a compound of formula Ba6N19. The compounds Ba2NBr and BagNl9 disintegrate readily on exposure to the atmosphere. a specimen of this compound. 12) J . University PressPrinceton, N.J., 1949, p. 704. as well as W. E. Cuss, J. Amer. chem. Soc. 64,785 (1942) give a b.p. of 223-225 "C for 2-phenyl o x~l e .

Aromatic polyethers, polysulfones, and polyketones as laminating resins. V. Polymers containing acetylenic side groups

“…m These polymers with acetyl groups in the backbone were then converted into p-chloro unsaturated aldehydes by the Vilsmeyer reaction. [11][12][13] This reaction gives 90% yield and above. The scheme of the reaction is given in By treating the p-chloroaldehyde polymers with a base the respective acetylene polymers could be prepared (90% conversion and above).…”

“…version of an acetyl group into an acetylene group is a known reaction for simple m o l e~u l e s ,~~-~3 we did these reactions on the respective acetylcontaining polymers. Terpolymers of type A were obtained from a Friedel-Crafts type polymerization of 4,4'-diphenoxydiphenyl sulfone (I), 2,4diphenoxyacetophenone (11), isophthaloyl chloride (IPC), and terephthaloyl chloride (TPC), AlC13 being used as catalyst. The composition and properties of the polymers are given in Table I.…”

Alkynes From Furans: A General Fragmentation Method Applied to the Synthesis of the Proposed Structure of Aglatomin B

“…[1] Consequently,t he development of efficient and practical methods to synthesize alkynes has attracted considerable attention from the chemistry community.Among various methods for alkyne synthesis, alkyne-forming fragmentations [2] play aunique role since they offer as traightforward means to the structural modification of complex molecules.The history of such reaction manifolds can be traced back to 1963 when Bodendorf reported the first example of an alkyne-forming fragmentation of b-chloroacroleins ( Figure 1a). [3] Shortly afterward, the venerable Eschenmoser-Tanabe fragmentation was invented to convert a,b-epoxy ketones into either acetylenic ketones or aldehydes via the intermediacyo ft osylhydrazones. [4] Subsequent variations of this classical method utilized reactions of b-halo, [5] b-phenylseleno, [6] or b-tosylhydrazino-a,b-unsaturated ketones [7] with either an alkylithium or NaOMe to access alkynyl functionalities.M ore recently,t he group of Dudley extended the reaction scope to versatile vinylogous acyl triflates wherein av ariety of alkynyl ketones,a lcohols,a nd amides were afforded as products.…”

“…Aglatomin B( 1;p roposed structure) is ar epresentative 16,17-seco pregnane natural product that was isolated from A. Tomentosa alongside the cytotoxic compound rocaglaol (Figure 1b). [11] From as tructural perspective,a glatomin Bp ossesses a d-lactone ring which is prevalent in various natural products such as limonin (2) [12] and quassin (3). [13] Retrosynthetic analysis of aglatomin Bbydisconnection at the lactone linkage led to the alkynoic acid 4 as ap otential precursor.…”

Alkynes From Furans: A General Fragmentation Method Applied to the Synthesis of the Proposed Structure of Aglatomin B

“…[16] However,t he carbon framework of furans remains largely intact in these processes as furan fragmentation involving the cleavage of CÀCb ond is rare. No desired product was obtained in the absence of singlet oxygen (entries 2a nd 3), and omission of the basic hydrolysis step led to products in much lower yields owing to the presence of the anhydride (structure not shown, see 22 in Scheme 2; entry 4). No desired product was obtained in the absence of singlet oxygen (entries 2a nd 3), and omission of the basic hydrolysis step led to products in much lower yields owing to the presence of the anhydride (structure not shown, see 22 in Scheme 2; entry 4).…”