Design, synthesis, and evaluation of chiral thiophosphorus acids as organocatalysts

• Karen R. Winters and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2022, 18, 1471–1478, doi:10.3762/bjoc.18.154

• cross-coupling [34] in excellent yield. Esterification of 6 with monomethyl H-phosphonate tert-butylamine salt [35] resulted in the mixed H-phosphonate ester 7 in excellent yield. Cyclization using our homolytic aromatic substitution methodology [36] gave P-heterocycle 8 in modest yield. Other methods

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• through Horner–Wardsworth–Emmons olefination of the known precursors 111 and 112, which are prepared from ᴅ-mannitol and ʟ-lactic acid methyl ester, respectively. The synthesis commenced with the reaction between aldehyde 111 and phosphonate ester 112 using Ba(OH)2·8H2O to provide the unsaturated ketone

The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• . Keywords: bromotrimethylsilane; McKenna reaction; organophosphorus acid; oxazole; phosphonate ester; Introduction The McKenna reaction is a tool for the synthesis of organophosphorus acids from their esters and known for over 40 years [1][2]. The importance of this class of compounds is widely recognized

• reagent of choice for phosphonate ester cleavage, compared with its more and less reactive analogs, iodotrimethylsilane (ITMS) [11][12] and chlorotrimethylsilane (CTMS) [13], respectively. While being one of the most popular methods for the deprotection of organophosphorus esters, the McKenna reaction may

• cleaved upon exposure to BTMS. All model compounds were prepared according to literature procedures and thoroughly dried before use [22][23][24][25]. Even though the McKenna reaction could be completed within a couple of hours, the rate of the reaction depends on the structure of the phosphonate ester

Synthesis of C-glycosyl phosphonate derivatives of 4-amino-4-deoxy-α-ʟ-arabinose

• Lukáš Kerner and
• Paul Kosma

Beilstein J. Org. Chem. 2020, 16, 9–14, doi:10.3762/bjoc.16.2

• α-ʟ-anomeric arabino- and ribo-configured methyl phosphonate esters. In addition, the monomethyl phosphonate glycal intermediates were converted into n-octyl derivatives followed by subsequent selective removal of the methyl phosphonate ester group and hydrogenation to give the octylphosphono

• purification (Scheme 2). The equatorial arrangement of the C-glycosyl linkage was supported from the large value of the coupling constant J1,2 (9.5 Hz), indicating a 1,2-trans orientation of the respective protons. The monomethyl phosphonate ester 9 was then subjected to alkylation reactions in order to allow

• phosphonate ester derivatives 13 and 15 in good yields. For the future synthesis of deprotected glycal ester derivatives containing prenyl units, benzyl groups will have to be exchanged for protecting groups that can be removed under nonhydrogenolytic conditions, e.g., silyl ether protecting groups. In

An improved synthesis of adefovir and related analogues

• David J. Jones,
• Eileen M. O’Leary and
• Timothy P. O’Sullivan

Beilstein J. Org. Chem. 2019, 15, 801–810, doi:10.3762/bjoc.15.77

• form alcohol 4 and further base-mediated alkylation with tosylate 5 affords phosphonate ester intermediate 6. Subsequent dealkylation of 6 using trimethylsilyl bromide (TMSBr) gives adefovir (1). The related analogue tenofovir, developed as an anti-HIV agent, may be prepared in a similar manner [37][38

• potential. Given the issues encountered in employing MTB, we next investigated the introduction of the phosphonate ester as the nucleophile rather than as the electrophile (Figure 2). Commercially available alcohol 10 was prepared by adapting a previously reported literature procedure where diethyl

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• , entries 2, 7 and 12). Gebbink and co-workers anchored the HG-type catalyst 79 to cutinase, a serine hydrolase [75]. The phosphonate ester moiety acts as a suicide inhibitor forming an irreversible covalent bond to a serine residue present in the active site of the enzyme. Assembly of ArM 8 occurs at pH 5

One-pot synthesis of enantiomerically pure N-protected allylic amines from N-protected α-amino esters

• Gastón Silveira-Dorta,
• Sergio J. Álvarez-Méndez,
• Víctor S. Martín and
• José M. Padrón

Beilstein J. Org. Chem. 2016, 12, 957–962, doi:10.3762/bjoc.12.94

• , and N-Ac and N-Boc glutamic acid dialkyl esters, this time using a stabilized phosphonate ester [18]. This strategy was used later on in the synthesis of aminopeptidase A inhibitors [19]. Similarly, N-methylproline methyl ester was reacted in a similar one-pot fashion during the synthesis of nine

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• structurally diverse small molecules starting with solid-supported phosphonate 213. In this regard, they have shown the use of a RRM protocol to prepare the bicyclic product 218 as well as tricyclic product 217. To this end, the phosphonate ester 213 reacted with a wide variety of aldehydes 214 such as aryl

Relay cross metathesis reactions of vinylphosphonates

• Raj K. Malla,
• Jeremy N. Ridenour and
• Christopher D. Spilling

Beilstein J. Org. Chem. 2014, 10, 1933–1941, doi:10.3762/bjoc.10.201

• ]. Therefore, given the propensity for vinylphosphonates to undergo RCM, it was proposed that an allyl phosphonate ester 14 would act as an initial site of metathesis, which would lead to a relay cross metathesis and thus render vinylphosphonates reactive. Results and Discussion A series of cross metathesis

• separation of the crude product gave the unsaturated ester 16b in 86% isolated yield. It is proposed that the Grubbs catalyst first reacts with the terminal alkene (Scheme 11) of the allyl phosphonate ester 21a to give the metal alkylidene 33. The metal alkylidene then reacts with the vinylphosphonate in a

4-Hydroxy-6-alkyl-2-pyrones as nucleophilic coupling partners in Mitsunobu reactions and oxa-Michael additions

• Michael J. Burns,
• Thomas O. Ronson,
• Richard J. K. Taylor and
• Ian J. S. Fairlamb

Beilstein J. Org. Chem. 2014, 10, 1159–1165, doi:10.3762/bjoc.10.116

• , entry 2), a tosylate leaving group (Table 1, entry 4), and a halide (Table 1, entry 5). Somewhat more exotic functional groups such as a phosphonate ester (Table 1, entry 6) or a dimethyl acetal (Table 1, entry 7) were still tolerated in the reaction, albeit in more modest yields. A variety of alkylated

Synthesis and redox behavior of new ferrocene- π-extended- dithiafulvalenes: An approach for anticipated organic conductors

• Abdelwareth A. O. Sarhan,
• Omar F. Mohammed and
• Taeko Izumi

Beilstein J. Org. Chem. 2009, 5, No. 6, doi:10.3762/bjoc.5.6

• multicomponent electron donor systems by the Wittig–Horner reaction of the respective phosphonate ester 6 with different ferreocenylketones using the modifications introduced onto the reaction. The redox chemistry of the ferreocenylketones and these new π-conjugated hybrids 8, 10 and 11 has been studied using