摘要:

Abstract(SP)‐9‐Anthryl(l‐menthyloxy)phenylphosphine‐borane and (SP)‐(1‐l‐menthyloxy)benzo[b]phosphole‐borane were synthesized, and their structures were characterized by X‐ray crystallographic analysis. The latter compound was reduced by lithium naphthalenide at −78°C with cleavage of the PO bond, and the subsequent reaction with electrophiles afforded the corresponding tertiary phosphine‐boranes possessing good to excelle

ISSN:1042-7163    

DOI:10.1002/hc.520060204

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractEleven derivatives of the clinically useful, antimalarial, 1,2,4‐trioxane artemisinin have been synthesized in only several steps from commercial cyclohexanones. Of these simple, tricyclic 1,2,4‐trioxanes, 10 showed considerable in vitro antimalarial activity, with one being as potent as artemisinin. Some structure‐activity relationship generalizations are made from this series of artemisinin analogs. Triethylsilyl hydrotrioxide (Et3SiOOOH), prepared in situ from ozone and triethylsilane, is shown to be a mild, fastacting, and effective dioxetane‐forming reagent with vinyl ethers and with a vinyl thioether on relatively small (50–100

ISSN:1042-7163    

DOI:10.1002/hc.520060205

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA series of diisopinocampheylhaloboranes and monoisopinocampheyldihaloboranes were synthesized by the reaction of the corresponding boranes with the respective HX or X2(X = halogen) or by the hydroboration of α‐pinene with the corresponding haloboranes. Stabilities of these haloboranes in various solvents were studied. Most of these haloboranes proved capable of reducing prochiral ketones to the alcohols with significant optical induction. When tested against a representative aromatic and aliphatic prochiral ketone, acetophenone and 3‐methyl‐2‐butanone, respectively, α‐phenethyl alcohol in 65–98% ee and 3‐methyl‐2‐butanol in 28–59% ee were obtained. Some of them exhibit

ISSN:1042-7163    

DOI:10.1002/hc.520060206

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA general method for the preparation of dissymmetric olefins has been developed. The anion derived from an enantiomerically enriched P‐(phenylthiomethyl)phosphonamidate(1,3,2‐oxazaphosphorinane2‐oxide) was added to 4‐tert‐butylcyclohexanone with excellent diastereoselectivity. The β‐hydroxyphos‐phonamidate was converted into a (phenylthio)‐methylidene with excellent stereospecificity using a novel electrophile‐promoted olefination that employed trityl triflate and 2,6‐lutidine in warm acetonitrile. The vinyl sulfide underwent nickel‐catalyzed coupling with Grignard and dialkylzinc reagents to produce (S)‐4‐(tert‐butyl)alkylidenecyclohexanes with modera

ISSN:1042-7163    

DOI:10.1002/hc.520060207

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSome 5H,7H‐dibenzo[b,g][1,5]dithiocin oxides (4–8) and their related compounds9–13were prepared and the assignment of the most favorable conformation was carried out on the basis of the characteristic1H NMR spectral data. Only a single conformer (BC: boatchair form) exists for4,5, and8–13, while two conformers (BC and TB: twist‐boat form) are apparent for6and7. Oxidation and methylation of4gave exclusively a single geometrical isomer (8and13, respectively). These results are interpreted as a sterically preferential attack of electrophiles on the BC conformer of the starting material. A 1,5‐oxygen shift of4occurred smoothly to give6in the presence of trifluoroacetic acid in CDCl3solution. The mechanistic investigation is described briefly. Differences in chemical behavior between dibenzodithiocin 12‐oxide4and dibenzothiazocine 12‐oxide2are also discussed on the basis of the conforma

ISSN:1042-7163    

DOI:10.1002/hc.520060208

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractReactions of a sterically crowded 1,3,2‐dithiastannetane derivative bearing 2,4,6‐tris[bis(trimethylsilyl)methyl]phenyl (=Tbt) and 2,4,6‐triisopropylphenyl (=Tip) groups on the tin atom are described. Both thermolysis and photolysis of the 1,3,2‐dithiastannetane [Tbt(Tip)SnS2CPh2] resulted in the formation of products derived from the corresponding stannanethione [Tbt(Tip)Sn=S], while the oxidation reaction bym‐chloroperbenzoic acid gave a novel tincontaining heterocyclic system, an 1,2,4,5‐oxadithiastannolane

ISSN:1042-7163    

DOI:10.1002/hc.520060209

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractTreatment of 2,2,4,4‐tetramethyl‐1,5‐diphenyl‐6,7‐dithiabicyclo[3.1.1]heptane 6‐endo‐oxide (2) with Montmorillonitc K 10 in dichloromethane gave 2,2,‐4,4‐tetramethyl‐1,5‐diphenyl‐7,8‐dithia‐6‐oxabicyclo‐[3.2.1]octane (6) (11%) with recovery of2(87%). Under similar reaction conditions, the 6‐exo‐oxide7and the sulfenate6gave a mixture of6(21%),2(67%), and7(9%) and a mixture of2(89%) and6(9%), respectively. These results indicate the relative thermodynamic stabilities of the three compounds to be2>6>7. PM3 calculations on these compounds showed the heats of formation (kcal/mol) to be in the following order:6(44.12783),2(57.46721), and7(59.37918). The driving force of this unusual 1,2‐rearrangement of2and7to6would be the release of the ring strain of the bicyclo[3.1.1]he

ISSN:1042-7163    

DOI:10.1002/hc.520060210

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA novel cyclic sulfilimine, 2‐methyl‐2,4,1‐benzodithiazin‐2‐ium‐1‐ide (4) was synthesized by deprotonation of the corresponding azasulfonium salt (3) with base. The compound4was oxidized with potassium permanganate to afford the sulfoximine5, exclusively. On refluxing in several solvents, compound4underwent a ring contraction to afford benzothiazole (8) via the 1,2‐imino shift. The reaction of4with a variety of electrophiles, such as dialkyl acetylenedicarboxylate, acylating agents, diphenylcyclopropenone, and phenyl isocyanate, afforded ringopened adducts. Synthetic approaches to cyclic disulfonium ylides are

ISSN:1042-7163    

DOI:10.1002/hc.520060211

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractFT‐IR spectroscopy and a special mathematical program were used for the real‐time monitoring of the mechanistic path of the reaction of S‐ethyl‐N,N‐tetraethyldiamidothiophosphite with [CpMn(CO)‐2NO]+BF 4−. The formation of a few intermediat

ISSN:1042-7163    

DOI:10.1002/hc.520060212

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe coupling of 1,2‐bis(o‐hydroxybenzamido)ethane1with two equivalents of the appropriate arenediazonium chloride in aqueous sodium hydroxide afforded the corresponding 1,2‐bis(2‐hydroxy‐5‐arylazobenzoylamino)ethanes4–6. The latter were converted to the corresponding dipotassium salts7–9, which were reacted with the appropriate dihalo compound or ditosylate in boiling DMF to give the corresponding 14‐17‐membered macrocyclic bis‐azo‐crowndilactams10–18in 58–65% yields. Compound14was N‐alkylated to give the correspondi

ISSN:1042-7163    

DOI:10.1002/hc.520060213

出版商:VCH Publishers, Inc.    

年代:1995

数据来源: WILEY