Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Group 13 sulfides imines

All cationically polymerizable rings in the third group are n donors. Cyclic ethers, acetals, sulfides, imines, lactones, and lactams belong to this group ... [Pg.158]

The method of in situ generation of diazo compounds from N-tosylhydrazone salts proved to be quite efficient for aziridination. When sulfide 19 was employed as a catalyst, moderate to good yields and excellent enantioselectivities were obtained with a range of aromatic imines. The trans cis ratios of the products varied in the range of 2-8 1, dependent on the N-protecting group of imines. Notably, the aziridinations of aliphatic imines (cyclohexyl imine, tert-butyl imine) and benzophenone-imine also proceeded well, giving the aziridine products in 50-53% yields and 73-98% ee [39]. [Pg.562]

Saito has recently reported high yields and enantioselectivities in aziridine synthesis through reactions between aryl- or vinyl-substituted N-sulfonyl imines and aryl bromides in the presence of base and mediated by a chiral sulfide 122 (Scheme 1.41) [66]. Aryl substituents with electron-withdrawing and -donating groups gave modest transxis selectivities (around 3 1) with high enantioselectiv-... [Pg.32]

It is well known that aziridination with allylic ylides is difficult, due to the low reactivity of imines - relative to carbonyl compounds - towards ylide attack, although imines do react with highly reactive sulfur ylides such as Me2S+-CH2-. Dai and coworkers found aziridination with allylic ylides to be possible when the activated imines 22 were treated with allylic sulfonium salts 23 under phase-transfer conditions (Scheme 2.8) [15]. Although the stereoselectivities of the reaction were low, this was the first example of efficient preparation of vinylaziridines by an ylide route. Similar results were obtained with use of arsonium or telluronium salts [16]. The stereoselectivity of aziridination was improved by use of imines activated by a phosphinoyl group [17]. The same group also reported a catalytic sulfonium ylide-mediated aziridination to produce (2-phenylvinyl)aziridines, by treatment of arylsulfonylimines with cinnamyl bromide in the presence of solid K2C03 and catalytic dimethyl sulfide in MeCN [18]. Recently, the synthesis of 3-alkyl-2-vinyl-aziridines by extension of Dai s work was reported [19]. [Pg.41]

The sulfide groups in mesoionic 1,3,4-thiadiazolium salts are activated toward nucleophilic substitution. The mercapto substituent of the thiadiazolium salt 117 can be displaced by cyclohexylamine to afford the 2//-thiadiazol-imine 118 (Equation 37) <2004BML4607>. [Pg.588]

An alternative method of synthesizing the pyrazine compounds was described by Ghosh et al, and the synthesis is shown is Scheme 32 [78]. Reaction of a 1,2-dione (124) with a 1,2-diamine (125) to form an imine intermediate followed by spontaneous oxidation of the dihydropyrazine intermediate, formed the protected pyrazine compound 126. The free phenol 127 was obtained by removal of the methyl-protecting groups with a boron trifluoride-dimethyl sulfide complex. Similar compounds were prepared via the same method by Simoni et al. [79]. [Pg.45]

Complexity is added to the study of this system by the ready functionalization of the sulfur atom by alkylation, oxidation and imination. 5-Alkylation to produce a compound such as (9) <76T1873) affords a system in which either of two possible chair conformers possesses an axial t-butyl group, and this system therefore exists preferentially in a twist conformation (10). Where no such conflicts occur the sulfur substituent adopts the equatorial position in a chair form. Inversion of configuration at sulfur in cyclic sulfides has been investigated in the system (11) (12) and the corresponding ylides (13) (14) (77JA2337). [Pg.888]

BTIB oxidations of aromatic ethers in which sulfido groups are tethered to the ring provide access to heterocyclic sulfides [64], while related oxidations of azido-tethered analogs lead to quinone imines and/or their dimethyl ketals... [Pg.146]


See other pages where Group 13 sulfides imines is mentioned: [Pg.125]    [Pg.562]    [Pg.261]    [Pg.303]    [Pg.265]    [Pg.1150]    [Pg.88]    [Pg.237]    [Pg.57]    [Pg.111]    [Pg.299]    [Pg.248]    [Pg.54]    [Pg.265]    [Pg.836]    [Pg.265]    [Pg.1097]    [Pg.299]    [Pg.261]    [Pg.119]    [Pg.120]    [Pg.224]    [Pg.76]    [Pg.372]    [Pg.742]    [Pg.54]    [Pg.462]    [Pg.23]    [Pg.5016]    [Pg.53]    [Pg.96]    [Pg.23]    [Pg.140]    [Pg.68]    [Pg.72]    [Pg.40]    [Pg.30]    [Pg.635]   
See also in sourсe #XX -- [ Pg.445 ]




SEARCH



Group sulfides

Imine groups

© 2024 chempedia.info