ChemInformVolume 35, Issue 17 Natural Products Organophosphorus and Nitro-Substituted Sulfonate Esters of 1-Hydroxy-7-azabenzotriazole as Highly Efficient Fast-Acting Peptide Coupling Reagents. Louis A. Carpino, Louis A. Carpino Dep. Chem., Univ. Mass., Amherst, MA 01003, USASearch for more papers by this authorJusong Xia, Jusong Xia Dep. Chem., Univ. Mass., Amherst, MA 01003, USASearch for more papers by this authorChongwu Zhang, Chongwu Zhang Dep. Chem., Univ. Mass., Amherst, MA 01003, USASearch for more papers by this authorAyman El-Faham, Ayman El-Faham Dep. Chem., Univ. Mass., Amherst, MA 01003, USASearch for more papers by this author Louis A. Carpino, Louis A. Carpino Dep. Chem., Univ. Mass., Amherst, MA 01003, USASearch for more papers by this authorJusong Xia, Jusong Xia Dep. Chem., Univ. Mass., Amherst, MA 01003, USASearch for more papers by this authorChongwu Zhang, Chongwu Zhang Dep. Chem., Univ. Mass., Amherst, MA 01003, USASearch for more papers by this authorAyman El-Faham, Ayman El-Faham Dep. Chem., Univ. Mass., Amherst, MA 01003, USASearch for more papers by this author First published: 05 April 2004 https://doi.org/10.1002/chin.200417192AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References Louis A. Carpino, Jusong Xia, Chongwu Zhang, Ayman El-Faham, Organophosphorus and Nitro-Substituted Sulfonate Esters of 1-Hydroxy-7-azabenzotriazole as Highly Efficient Fast-Acting Peptide Coupling Reagents., J. Org. Chem., 2004, 69, 62–71. 10.1021/jo0300183 CASPubMedWeb of Science®Google Scholar Volume35, Issue17April 27, 2004 ReferencesRelatedInformation

The known but long-neglected compound HODhat was shown to be in certain situations a useful peptide coupling additive. Uronium and phosphonium salts with HODhat built into the system were also useful stand-alone coupling reagents. Comparisons with related additives and coupling reagents showed that the new systems were sometimes more and sometimes less effective than previously described systems in the case of stepwise and segment couplings. Applications to assembly of the model decapeptide ACP showed that HDATU was far more effective than HDTU and more effective than HATU under some conditions.

Organophosphorus esters 9, 10, 14, and 15 prepared via reaction of diethyl- and diphenylphosphoryl chloride, di(o-tolyl)phosphinyl chloride, and 2,8-dimethylphenoxaphosphinyl chloride with HOAt are excellent coupling reagents for peptide synthesis which are generally superior to their uronium/guanidinium analogues and HOBt- or HODhbt-derived phosphate ester counterparts in minimizing loss of configuration during segment coupling. The phosphinyl analogues are more shelf-stable than the phosphoryl systems. The new reagents have been tested in segment couplings leading to two tripeptides (20, 21) and a hexapeptide 22. Outstanding utility is also shown for the solid-phase assembly of the ACP decapeptide. Similar results were obtained with the 2- and 4-nitro- and 2,4-dinitrophenylsulfonyl esters derived from HOAt.

LnCl3 reacted with C6H5CH2C5H4Na in THF (tetrahydrofuran) in the ratio 1:1 at room temperature for 1 h giving C6H5CH2C6H4LnCl2·nTHF, which reacted with C8H8K2/THF and the crystals obtained were recrystallized in DME to yield the title complex. The crystal structure of (C8H8) Ln (C6H5CH2C5H4)·DME was determined revealing that the Gd complex has one conformation. One benzylcyclopentadienyl (η5), one cyclooctatetraenyl (η8) and the two oxygen atoms of DME (dimethoxyethane) are coordinated to Gd with the effective coordination number of 10.

NdCl 3 reacted with C 6 H 5 CH 2 C 5 H 4 Na in the ratio 1:1 at -78°C giving [C 6 H 5 CH 2 C 5 H 4 NdCl 2 · nTHF], which then was reacted with C 8 H 8 K 2 /THF to yield the title complex [(C 8 H 8 ) 3 (C 6 H 5 CH 2 C 5 H 4 )Nd 2 K(THF) 3 ] (C 6 H 5 CH 2 C 5 H 4 = benzylcyclopentadienyl). The crystal structure of the Nd complex was determined by X-ray diffraction and revealed that the benzyl group is coordinated to the potassium atom to form a new type of trinuclear complex [(η 8 -C 8 H 8 )Nd(μ 2 -η 8 -C 8 H 8 K(THF) (η 3 -C 6 H 5 CH 2 -μ 2 — η 5 — C 5 H 4 )Nd (THF) 2 (η 8 -C 8 H 8 )]. Copyright © 1996 Elsevier Science Ltd

[(C 6 H 5 CH 2 C 5 H 4 ) 2 GdCl.THF] 2 (1) and (C 6 H 5 CH 2 C 5 H 4 ) 2 ErCl.THF (2) were prepared by the reaction of LnCl 3 (LnGd, Er) with benzylcyclopentadienyl sodium in THF and characterized by elemental analysis, IR, 1 H NMR, 13 C NMR, MS and thermal gravimetry. The crystal structures of both compounds were determined. Complex 1 is dimeric and its structure belongs to the monoclinic, P2 1 /c space group with a =1.1432(2), b =1.2978(2), c =1.7604(3) nm, β =108.75(2), V =2.4732(9) nm 3 , Z =2(four monomers), D c “1.54 g.cm −3 . R =0.0342 and R w “0.0362. Complex 2 is monomer and its structure belongs to the orthorhombic, P 2 1 2 1 2 1 space group with a =0.8645(2), b =1.1394(3), c =2.5289(4) nm, V =2.4919(9) nm 3 , Z =4, D c “1.56 g.cm −3 . R =0.0514, R w “0.0529. The determination of the crystal structure shows that in complex 1 the benzyl groups on the cyclopentadienyls coordinated to Gd 3+ are located in the opposite direction (139°); in complex 2 the benzyl groups on the cyclopentadienyls coordinated to Er 3+ are located in the same direction (6.5°).

[(C6H5CH2C5H4)(2)GdCl . THF](2) (1) and (C6H5CH2C5H4)(2)ErCl . THF (2) were prepared by the reaction of LnCl(3) (Ln=Gd, Er) with benzylcyclopentadienyl sodium in THF and characterized by elemental analysis, IR, H-1 NMR, C-13 NMR, MS and thermal gravimetry. The crystal structures of both compounds were determined. Complex 1 is dimeric and its structure belongs to the monoclinic, P2(1)/c space group with a=1.1432(2), b=1.2978(2), c=1.7604(3) nm, beta=108.75(2), V=2.4732(9) nm(3), Z=2(four monomers), D-c=1.54 g . cm(-3). R=0.0342 and R(w)=0.0362. Complex 2 is monomer and its structure belongs to the orthorhombic, P2(1)2(1)2(1) space group with a=0.8645(2), b=1.1394(3), c=2.5289(4) nm, V=2.4919(9) nm(3), Z=4, D-c=1.56 g . cm(-3). R=0.0514, R(w)=0.0529. The determination of the crystal structure shows that in complex 1 the benzyl groups on the cyclopentadienyls coordinated to Gd3+ are located in the opposite direction (139 degrees); in complex 2 the benzyl groups on the cyclopentadienyls coordinated to Er3+ are located in the same direction (6.5 degrees).

用无水硝酸铈铵[(NH_4)_2Ce(NO_3)_6]与环戊二烯钠(C_5H_5Na)在四氢呋喃中按1:6摩尔比反应,得到(η~5-C_6H_5)_3Ce·OC_4H_8;用ErCl_3·nTHF与环辛二烯钾(C_8H_(11)K)按等摩尔比于-78℃反应,升至室温,再按1:2摩尔比加入C_5H_5Na,得到了(η~5-C_5H_5)_3Er·OC_4H_8.两配合物晶体结构测定结果表明都属单斜晶系P2_(1/n)空间群.Ce配合物与已测定过的(η~5-C_5H_5)_3Ln·OC_4H_8(Ln=La,PrNd,Gd,Dy,Y,Lu)的晶体结构不是同构物:而Er配合物则是同构物.Ce配合物中的Ce—O、Ce—Cent(环戊二烯环中心)和平均Ce—C(η~5)键长不符合镧系收缩规律,而Er配合物的键长符合.这说明在(η~5-C_5H_5)_3Ln·OC_4H_8同构系列中在Ce和Dy有两个断点,但不存在所谓的“钆断现象”,因为Y,Er,Lu配合物的Ln—O和Ln—C(η~5)和Ln—Centroid距离不大于Gd的相应值.

In order to stabilize the organolanthanide chlorides or dichlorides, some substituted cyclopentadienes are used as ligands. At present, several kinds of substituted cyclopentadienes, e. g. CH_3C_5H_5, C_5(CH_3)_5H, (CH_3)_3SiC_5H_5, t-C_4H_9C_5H_5, CH_3CH_2CH_2- C_5H_5, etc., have been used as the ligands. Benzylcyclopentadiene was synthesized in 1936. So far, however, very few studies on benzylcyclopentadiene as a ligand used in organometallic chemistry have been found. Only benzylcyclopentadienyl iron and uranium complexes have been reported. Recently, we synthesized benzylcyclopentadienyl lanthanide dichlorides. In this note, we report the syntheses and crystal structures of bisbenzylcyclopentadienyl lanthanide chlorides.

In recent years,the organometallic ehemistry of the lanthanide metals in low oxidation states has beenactively investigated.The synthesis of the low一valent lanthanide eomPlexes has the signifieant meanings ontheory and praeti