Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• tert-butyl ester function and finally hydrogenolytic opening of the isoxazolidine ring with simultaneous protection of the amino group (Scheme 18). By Diels–Alder reaction Acylnitroso derivative 74 prepared from methyl N-Boc-L-alaninate underwent Diels–Alder reaction with cyclopentadiene to produce

• [86][87][88] or a Diels–Alder reaction using acylnitroso compounds [89]. However, when compared with these multistep approaches hydroxylation of pyroglutamic acid derivatives seems to be the simplest option. Treatment of the lithium enolate of benzyl N-Boc-pyroglutamate (S)-86 with Davis oxaziridine

Oxidative cycloaddition of hydroxamic acids with dienes or guaiacols mediated by iodine(III) reagents

• Hisato Shimizu,
• Akira Yoshimura,
• Keiichi Noguchi,
• Victor N. Nemykin,
• Viktor V. Zhdankin and
• Akio Saito

Beilstein J. Org. Chem. 2018, 14, 531–536, doi:10.3762/bjoc.14.39

• , Winnipeg, MB R3T 2N2, Canada 10.3762/bjoc.14.39 Abstract [Bis(trifluoroacetoxy)iodo]benzene (BTI) and (diacetoxyiodo)benzene (DIB) efficiently promote the formation of acylnitroso species from hydroxamic acids in the presence of various dienes to give the corresponding hetero-Diels–Alder (HDA) adducts in

• moderate to high yields. The present method could be applied to the HDA reactions of acylnitroso species with o-benzoquinones generated by the oxidative dearomatization of guaiacols. Keywords: acylnitroso; benzoquinone; cycloaddition; dearomatization; iodine(III); Introduction The hetero-Diels–Alder (HDA

• ) reaction of N-acylnitroso species with dienes provides the facile and highly stereoselective synthesis of 1,2-oxazines, which have been widely recognized as useful synthons in the synthesis of biologically active natural products [1]. Generally, in the presence of dienes, acylnitroso species are in situ

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

• –Alder reactions using alkyl- or arylnitroso dienophiles were reported by Wichterle [11] and Arbuzov [12][13] in 1947 and 1948, respectively. Among the early reported reactions using an acylnitroso compound as the dienophile, an interesting study by Kirby and Sweeny in 1973 [14] reported that the

• acylnitroso dienophile 5 was generated in the presence of thebaine (4) to selectively give the 1,2-oxazine 6 (Scheme 2). Several excellent reviews on nitroso hetero-Diels–Alder reactions have been published in the past, including general reviews on hetero-Diels–Alder reactions and their applications in

• -Diels–Alder reaction [16][27][28][29] and the most frequently used representatives are depicted in Figure 1. Compounds 1a–c will be studied in more detail in this review. Arylnitroso compounds are, in comparison to acylnitroso analogues, quite stable, and in many cases, they can be isolated and stored

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

• David Porter,
• Belinda M.-L. Poon and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275

• context there has been a renewed focus on the chemistry of acylnitroso species in recent times [12][13][14][15], in particular on α-hydroxyamination of carbonyl compounds via nitrosocarbonyl aldol reactions [16][17][18][19][20][21] and allylic hydroxyamination of alkenes via nitroso–ene reactions [22][23

• ][24][25][26]. Several new developments in the related hetero-Diels–Alder reaction of acylnitroso species have also been reported recently [27][28][29][30]. These methodologies generally involve in situ generation of the acylnitroso species, achieved using a variety of oxidants including vanadium- [28

• ) revealed two peaks with equal peak areas (tR = 8.6 and 8.8 minutes); the same peaks in the same ratio were observed using a reference sample of racemic 9. Several groups have recently reported efficient methods for the asymmetric hydroxyamination of carbonyl compounds using acylnitroso species generated in