摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v67-466

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Epoxide ring opening reactions of methyl 2,3-anhydro-4-azido-4-deoxy-pentopyranosides with hydroxide ion and methoxide ion are described. The products obtained by reactions of the epoxides with hydroxide ion are related, by preparation of their 2,3-di-O-methanesulfonyl derivatives, to known compounds or their enantiomers. Opening of the α-d(andl)-riboepoxides with methoxide ion gave monomethylated products which were characterized by nuclear magnetic resonance analysis of their acetates. The relative yields of the two major products obtained in each case are not accounted for, in some cases, by consideration of only steric and inductive effects.

ISSN:0008-4042    

DOI:10.1139/v67-467

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The addition reaction R2EX + CF3C≡CCF3 → R2EC(CF3)=C(CF3)X has been investigated further (E = P and N); 1:1 adducts have been obtained from (C2H5)2PH, (CF3)2PH, (C6H5)2P—P(C6H5)2, and (CH3)2NCl, but not from (CH3)2PCl or (CH3)2P—P(CH3)2. (CF3)2PH also gives a 2:1 adduct. Triphenylphosphine causes the butyne to polymerize at − 78°. A similar but slower reaction takes place with trimethylamine. In the presence of water, trimethylamine and the butyne give the bis(butenyl) ethercis,trans(CF3CH=CCF3)2O as the major product.

ISSN:0008-4042    

DOI:10.1139/v67-468

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The infrared spectra of caffeine and its salts show that protonation occurs at position 9, the free nitrogen atom in the imidazole ring. N+H stretching and in-plane and out-of-plane bending modes have been assigned with the help of the deuterated salts. Protonation causes changes in some ring modes, accompanied by shifts in the carbonyl stretching frequencies to higher values.

ISSN:0008-4042    

DOI:10.1139/v67-469

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

From the infrared spectra of theobromine salts it is concluded that the salts are probably arranged in hydrogen-bonded centrosymmetric pairs involvinginteractions.anion−hydrogen bonds are formed by protonation of the free nitrogen atom (N9) in the imidazole ring. Infrared absorption bands arising from the former hydrogen bond constantly appear near 3 000 cm−1, whereas those from the latter shift from 2 580 to 3 300 cm−1, depending on the anion. In-plane NH and N+H deformation modes give bands near 1 485 and 1 160 cm−1, respectively. Out-of-plane NH modes have been located, but precise assignments are not possible.The assignments for some other bands which show deuteration shifts are detailed, and the carbonyl stretching vibrations which increase in frequency on protonation of the free base are identified.

ISSN:0008-4042    

DOI:10.1139/v67-470

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Thiazolo[3·2-a]benzimidazole (I) and several of its derivatives were synthesized by annelation of the thiazole ring to a benzimidazole. The intermediate 3-hydroxy-2,3-dihydrothiazolo[3·2-a] benzimidazoles were identified and the 3-position of the hydroxyl group was established by oxidation to 3-(2H)-thiazolo[3·2-a]benzimidazolone. Tautomerism of the 3-hydroxy-2,3-dihydrothiazolo[3·2-a]benzimidazoles was also investigated.3-Hydroxy-2,3-dihydrothiazolo[3·2-a]benzimidazole and the corresponding 3-methyl compound were found to undergo nitrogen acetylation and rearrangement under acetylating conditions.

ISSN:0008-4042    

DOI:10.1139/v67-471

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The variables important to the development of pyrolysis gas chromatography as a means of identification of liquids and gases were studied by placing a pyrolysis tube at the inlet of a gas chromatographic column. The pyrolysis conditions can be controlled to limit the formation of methane and to yield the maximum quantities of other products for identification of the parent compounds. Conditions that reduce methane formation are the absence of air, low temperatures, a long residence time, and the use of quartz rather than stainless-steel pyrolysis tubes. There is a limited range of pyrolysis temperatures that permits the formation and observation of all products in a pyrogram.

ISSN:0008-4042    

DOI:10.1139/v67-472

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The addition of vinylmagnesium chloride to 2,3-O-isopropylidene-d-glyceraldehyde (I) gave a mixture of the epimeric pentene derivatives II and V, which were separated by preparative gas–liquid chromatography. Ozonolysis and subsequent deketalization of the individual epimers gaved-threose andd-erythrose, respectively, in yields of ca. 40%. This represents a method of lengthening an aldose carbon chain by one carbon atom.

ISSN:0008-4042    

DOI:10.1139/v67-473

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Ultraviolet irradiation of 3-phenyl-2-cyclohexenone has been found to give a single photo dimer, whose structure has been established as thecis–anti–cishead-to-head cyclobutane derivative X.

ISSN:0008-4042    

DOI:10.1139/v67-474

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Ultraviolet irradiation of 3-(p-anisyl)-2-cyclohexenone and 3-(p-nitrophenyl)-2-cyclohexenone has been found to give a single photodimer in each case, the structures of which have been established as thecis–anti–cishead-to-head cyclobutane derivatives XI and XIII, respectively.

ISSN:0008-4042    

DOI:10.1139/v67-475

出版商:NRC Research Press    

年代:1967

数据来源: NRC